server/mssql support delete mutations (close hasura/graphql-engine#7626)

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2691
Co-authored-by: Abby Sassel <3883855+sassela@users.noreply.github.com>
Co-authored-by: Rakesh Emmadi <12475069+rakeshkky@users.noreply.github.com>
GitOrigin-RevId: 8b66cc30e8e036ee56a5267c1d2f308155951ae9

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Next release
 (Add highlights/major features below)
 
+- server: implement delete mutations for MS SQL Server (closes #7626)
 - server: fix JSON path in error when parsing sources in metadata (fix #7769)
 - server: log locking DB queries during source catalog migration
 - server: fix to allow remote schema response to contain an "extensions" field (#7143)

cabal.project

@@ -87,10 +87,10 @@ source-repository-package
   location: https://github.com/hasura/ekg-json.git
   tag: 098e3a5951c4991c823815706f1f58f608bb6ec3
 
--- This is v1.2.3.2 with https://github.com/haskell/text/pull/348 
+-- This is v1.2.3.2 with https://github.com/haskell/text/pull/348
 -- cherry-picked. When 1.3 is released we can move from this fork.
 source-repository-package
   type: git
   location: https://github.com/hasura/text.git
-  tag: 874c3164fadf39a83382359d2b6ce941a3e134da 
+  tag: 874c3164fadf39a83382359d2b6ce941a3e134da
 

docs/graphql/core/databases/ms-sql-server/index.rst

@@ -40,7 +40,7 @@ Hasura currently supports queries, subscriptions, relationships and permissions
 Next up on our roadmap for Hasura + SQL Server:
 
 - Support for stored procedures & functions (`#7073 <https://github.com/hasura/graphql-engine/issues/7073>`__)
-- Mutations: Run inserts, updates, deletes, stored procedures and transactions securely on SQL Server over a GraphQL API (`#7074 <https://github.com/hasura/graphql-engine/issues/7074>`__)
+- Mutations: Run inserts, updates, stored procedures and transactions securely on SQL Server over a GraphQL API (`#7074 <https://github.com/hasura/graphql-engine/issues/7074>`__)
 - Event triggers: Trigger HTTP webhooks with atomic capture and atleast once guarantee whenever data changes inside the database (`#7075 <https://github.com/hasura/graphql-engine/issues/7075>`__)
 - Remote Joins: Join models in SQL Server to models from other API services (GraphQL or REST) (`#7076 <https://github.com/hasura/graphql-engine/issues/7076>`__)
 
@@ -66,6 +66,7 @@ Know more
   Getting Started <getting-started/index>
   Schema <schema/index>
   Queries <queries/index>
+  Mutations <mutations/index>
   Subscriptions <subscriptions/index>
 
 .. TODO: DB-COMPATIBILITY

docs/graphql/core/databases/ms-sql-server/mutations/delete.rst

@@ -0,0 +1,184 @@
+.. meta::
+   :description: Delete an object from MS SQL Server using a mutation
+   :keywords: hasura, docs, ms sql server, mutation, delete
+
+.. _ms_sql_server_delete:
+
+MS SQL Server: Delete mutation
+==============================
+
+.. contents:: Table of contents
+  :backlinks: none
+  :depth: 1
+  :local:
+
+Auto-generated delete mutation schema
+-------------------------------------
+
+**For example**, the auto-generated schema for the delete mutation field for a table ``article`` looks like the following:
+
+.. code-block:: graphql
+
+  delete_article (
+    where: article_bool_exp!
+  ): article_mutation_response
+
+  # response of any mutation on the table "article"
+  type article_mutation_response {
+    # number of affected rows by the mutation
+    affected_rows: Int!
+    # data of the affected rows by the mutation
+    returning: [article!]!
+  }
+
+  # single object delete
+  delete_article_by_pk (
+    # all primary key columns args
+    id: Int
+  ): article
+
+As you can see from the schema:
+
+- The ``where`` argument is compulsory to filter rows to be deleted. See :ref:`Filter queries <filter_queries>`
+  for filtering options. Objects can be deleted based on filters on their own fields or those in their nested objects.
+  The ``{}`` expression can be used to delete all rows.
+- You can return the number of affected rows and the affected objects (with nested objects) in the response.
+
+See the :ref:`delete mutation API reference <delete_syntax>` for the full specifications.
+
+.. note::
+
+  If a table is not in the default ``dbo`` MS SQL Server schema, the delete mutation field will be of the format
+  ``delete_<schema_name>_<table_name>``.
+
+Delete an object by its primary key
+-----------------------------------
+
+You can delete a single object in a table using the primary key.
+The output type is the nullable table object. The mutation returns the deleted
+row object or ``null`` if the row does not exist.
+
+
+**Example:** Delete an article where ``id`` is ``1``:
+
+.. graphiql::
+  :view_only:
+  :query:
+    mutation delete_an_object {
+      delete_article_by_pk (
+        id: 1
+      ) {
+        id
+        title
+        user_id
+      }
+    }
+  :response:
+    {
+      "data": {
+        "delete_article_by_pk": {
+          "id": 1,
+          "title": "Article 1",
+          "user_id": 1
+        }
+      }
+    }
+
+**Example:** Delete a non-existent article:
+
+.. graphiql::
+  :view_only:
+  :query:
+    mutation delete_an_object {
+      delete_article_by_pk (
+        id: 100
+      ) {
+        id
+        title
+        user_id
+      }
+    }
+  :response:
+    {
+      "data": {
+        "delete_article_by_pk": null
+      }
+    }
+
+.. note::
+
+   ``delete_<table>_by_pk`` will **only** be available if you have select permissions on the table, as it returns the deleted row.
+
+Delete objects based on their fields
+------------------------------------
+**Example:** Delete all articles rated less than 3:
+
+.. graphiql::
+  :view_only:
+  :query:
+    mutation delete_low_rated_articles {
+      delete_article(
+        where: {rating: {_lt: 3}}
+      ) {
+        affected_rows
+      }
+    }
+  :response:
+    {
+      "data": {
+        "delete_low_rated_articles": {
+          "affected_rows": 8
+        }
+      }
+    }
+
+
+Delete objects based on nested objects' fields
+----------------------------------------------
+**Example:** Delete all articles written by a particular author:
+
+.. graphiql::
+  :view_only:
+  :query:
+    mutation delete_authors_articles {
+      delete_article(
+        where: {author: {name: {_eq: "Corny"}}}
+      ) {
+        affected_rows
+      }
+    }
+  :response:
+    {
+      "data": {
+        "delete_authors_articles": {
+          "affected_rows": 2
+        }
+      }
+    }
+
+Delete all objects
+------------------
+
+You can delete all objects in a table using the ``{}`` expression as the ``where`` argument. ``{}`` basically
+evaluates to ``true`` for all objects.
+
+**Example:** Delete all articles:
+
+.. graphiql::
+  :view_only:
+  :query:
+    mutation delete_all_articles {
+      delete_article (
+        where: {}
+      ) {
+        affected_rows
+      }
+    }
+  :response:
+    {
+      "data": {
+        "delete_article": {
+          "affected_rows": 20
+        }
+      }
+    }

docs/graphql/core/databases/ms-sql-server/mutations/index.rst

@@ -0,0 +1,44 @@
+.. meta::
+   :description: Manage mutations on MS SQL Server with Hasura
+   :keywords: hasura, docs, ms sql server, mutation
+
+.. _ms_sql_server_mutations:
+
+MS SQL Server: Mutations
+========================
+
+.. contents:: Table of contents
+  :backlinks: none
+  :depth: 1
+  :local:
+
+Introduction
+------------
+
+GraphQL mutations are used to modify data on the server (i.e. write, update or delete data).
+
+Hasura GraphQL engine auto-generates mutations as part of the GraphQL schema from your MS SQL Server schema model.
+
+Data of all tables in the database tracked by the GraphQL engine can be modified over the GraphQL endpoint.
+If you have a tracked table in your database, its insert/update/delete mutation fields are added as nested
+fields under the  ``mutation_root`` root level type.
+
+Types of mutation requests
+--------------------------
+
+The following types of mutation requests are possible:
+
+.. toctree::
+  :maxdepth: 1
+
+  Delete <delete>
+
+.. TODO: DBCOMPATIBILITY
+
+  .. toctree::
+    :maxdepth: 1
+
+    Insert <insert>
+    Upsert <upsert>
+    Update <update>
+    multiple-mutations

server/src-lib/Hasura/Backends/MSSQL/FromIr.hs

@@ -29,6 +29,7 @@ module Hasura.Backends.MSSQL.FromIr
     jsonFieldName,
     fromInsert,
     fromDelete,
+    toSelectIntoTempTable,
   )
 where
 
@@ -47,6 +48,7 @@ import Hasura.RQL.Types.Column qualified as IR
 import Hasura.RQL.Types.Common qualified as IR
 import Hasura.RQL.Types.Relationship qualified as IR
 import Hasura.SQL.Backend
+import Language.GraphQL.Draft.Syntax (unName)
 
 --------------------------------------------------------------------------------
 -- Types
@@ -1113,8 +1115,9 @@ normalizeInsertRows IR.AnnIns {..} insertRows =
 --------------------------------------------------------------------------------
 -- Delete
 
+-- | Convert IR AST representing delete into MSSQL AST representing a delete statement
 fromDelete :: IR.AnnDel 'MSSQL -> FromIr Delete
-fromDelete (IR.AnnDel tableName (permFilter, whereClause) _ _) = do
+fromDelete (IR.AnnDel tableName (permFilter, whereClause) _ allColumns) = do
   tableAlias <- fromTableName tableName
   runReaderT
     ( do
@@ -1127,11 +1130,38 @@ fromDelete (IR.AnnDel tableName (permFilter, whereClause) _ _) = do
                   { aliasedAlias = entityAliasText tableAlias,
                     aliasedThing = tableName
                   },
+              deleteColumns = map (ColumnName . unName . IR.pgiName) allColumns,
               deleteWhere = Where [permissionsFilter, whereExpression]
             }
     )
     tableAlias
 
+-- | Convert IR AST representing delete into MSSQL AST representing a creation of a temporary table
+--   with the same schema as the deleted from table.
+toSelectIntoTempTable :: TempTableName -> IR.AnnDel 'MSSQL -> SelectIntoTempTable
+toSelectIntoTempTable tempTableName (IR.AnnDel {IR.dqp1Table = fromTable, IR.dqp1AllCols = allColumns}) = do
+  SelectIntoTempTable
+    { sittTempTableName = tempTableName,
+      sittColumns = map columnInfoToUnifiedColumn allColumns,
+      sittFromTableName = fromTable
+    }
+
+-- | Extracts the type and column name of a ColumnInfo
+columnInfoToUnifiedColumn :: IR.ColumnInfo 'MSSQL -> UnifiedColumn
+columnInfoToUnifiedColumn colInfo =
+  case IR.pgiType colInfo of
+    IR.ColumnScalar t ->
+      UnifiedColumn
+        { name = unName $ IR.pgiName colInfo,
+          type' = t
+        }
+    -- Enum values are represented as text value so they will always be of type text
+    IR.ColumnEnumReference {} ->
+      UnifiedColumn
+        { name = unName $ IR.pgiName colInfo,
+          type' = TextType
+        }
+
 --------------------------------------------------------------------------------
 -- Misc combinators
 
@@ -1187,6 +1217,7 @@ fromAlias (FromQualifiedTable Aliased {aliasedAlias}) = EntityAlias aliasedAlias
 fromAlias (FromOpenJson Aliased {aliasedAlias}) = EntityAlias aliasedAlias
 fromAlias (FromSelect Aliased {aliasedAlias}) = EntityAlias aliasedAlias
 fromAlias (FromIdentifier identifier) = EntityAlias identifier
+fromAlias (FromTempTable Aliased {aliasedAlias}) = EntityAlias aliasedAlias
 
 columnNameToFieldName :: ColumnName -> EntityAlias -> FieldName
 columnNameToFieldName (ColumnName fieldName) EntityAlias {entityAliasText = fieldNameEntity} =

server/src-lib/Hasura/Backends/MSSQL/Instances/Execute.hs

@@ -226,7 +226,7 @@ msDBMutationPlan ::
 msDBMutationPlan userInfo stringifyNum sourceName sourceConfig mrf = do
   go <$> case mrf of
     MDBInsert annInsert -> executeInsert userInfo stringifyNum sourceConfig annInsert
-    MDBDelete _annDelete -> throw400 NotSupported "delete mutations are not supported in MSSQL"
+    MDBDelete annDelete -> executeDelete userInfo stringifyNum sourceConfig annDelete
     MDBFunction {} -> throw400 NotSupported "function mutations are not supported in MSSQL"
   where
     go v = DBStepInfo @'MSSQL sourceName sourceConfig Nothing v
@@ -313,7 +313,7 @@ executeInsert userInfo stringifyNum sourceConfig annInsert = do
         Tx.unitQueryE fromMSSQLTxError $
           toQueryFlat $
             TQ.fromSetIdentityInsert $
-              SetIdenityInsert (_aiTableName $ _aiData insert) SetON
+              SetIdentityInsert (_aiTableName $ _aiData insert) SetON
 
       -- Generate the INSERT query
       let insertQuery = toQueryFlat $ TQ.fromInsert $ TSQL.fromInsert insert
@@ -383,6 +383,62 @@ executeInsert userInfo stringifyNum sourceConfig annInsert = do
             ExpressionProjection $ Aliased (SelectExpression (generateCheckConstraintSelect checkBoolExp)) "check_constraint_select"
        in emptySelect {selectProjections = [mutationOutputProjection, checkConstraintProjection]}
 
+-- Delete
+
+-- | Executes a Delete IR AST and return results as JSON.
+executeDelete ::
+  MonadError QErr m =>
+  UserInfo ->
+  Bool ->
+  SourceConfig 'MSSQL ->
+  AnnDelG 'MSSQL (Const Void) (UnpreparedValue 'MSSQL) ->
+  m (ExceptT QErr IO EncJSON)
+executeDelete userInfo stringifyNum sourceConfig deleteOperation = do
+  preparedDelete <- traverse (prepareValueQuery $ _uiSession userInfo) deleteOperation
+  let pool = _mscConnectionPool sourceConfig
+  pure $ withMSSQLPool pool $ Tx.runTxE fromMSSQLTxError (buildDeleteTx preparedDelete stringifyNum)
+
+-- | Converts a Delete IR AST to a transaction of three delete sql statements.
+--
+-- A GraphQL delete mutation does two things:
+--
+-- 1. Deletes rows in a table according to some predicate
+-- 2. (Potentially) returns the deleted rows (including relationships) as JSON
+--
+-- In order to complete these 2 things we need 3 SQL statements:
+--
+-- 1. SELECT INTO <temp_table> WHERE <false> - creates a temporary table
+--    with the same schema as the original table in which we'll store the deleted rows
+--    from the table we are deleting
+-- 2. DELETE FROM with OUTPUT - deletes the rows from the table and inserts the
+--   deleted rows to the temporary table from (1)
+-- 3. SELECT - constructs the @returning@ query from the temporary table, including
+--   relationships with other tables.
+buildDeleteTx ::
+  AnnDel 'MSSQL ->
+  Bool ->
+  Tx.TxET QErr IO EncJSON
+buildDeleteTx deleteOperation stringifyNum = do
+  let tempTableName = TSQL.TempTableName "deleted"
+      withAlias = "with_alias"
+      createTempTableQuery = toQueryFlat $ TQ.fromSelectIntoTempTable $ TSQL.toSelectIntoTempTable tempTableName deleteOperation
+  -- Create a temp table
+  Tx.unitQueryE fromMSSQLTxError createTempTableQuery
+  let deleteQuery = TQ.fromDelete tempTableName <$> TSQL.fromDelete deleteOperation
+  deleteQueryValidated <- toQueryFlat <$> V.runValidate (runFromIr deleteQuery) `onLeft` (throw500 . tshow)
+  -- Execute DELETE statement
+  Tx.unitQueryE fromMSSQLTxError deleteQueryValidated
+  mutationOutputSelect <- mkMutationOutputSelect stringifyNum withAlias $ dqp1Output deleteOperation
+  let withSelect =
+        emptySelect
+          { selectProjections = [StarProjection],
+            selectFrom = Just $ FromTempTable $ Aliased tempTableName "deleted_alias"
+          }
+      finalMutationOutputSelect = mutationOutputSelect {selectWith = Just $ With $ pure $ Aliased withSelect withAlias}
+      mutationOutputSelectQuery = toQueryFlat $ TQ.fromSelect finalMutationOutputSelect
+  -- Execute SELECT query and fetch mutation response
+  encJFromText <$> Tx.singleRowQueryE fromMSSQLTxError mutationOutputSelectQuery
+
 -- | Generate a SQL SELECT statement which outputs the mutation response
 --
 -- For multi row inserts:
@@ -400,28 +456,38 @@ mkMutationOutputSelect stringifyNum withAlias = \case
     projections <- forM multiRowFields $ \(fieldName, field') -> do
       let mkProjection = ExpressionProjection . flip Aliased (getFieldNameTxt fieldName) . SelectExpression
       mkProjection <$> case field' of
-        IR.MCount -> pure countSelect
+        IR.MCount -> pure $ countSelect withAlias
         IR.MExp t -> pure $ textSelect t
-        IR.MRet returningFields -> mkSelect JASMultipleRows returningFields
+        IR.MRet returningFields -> mkSelect stringifyNum withAlias JASMultipleRows returningFields
     let forJson = JsonFor $ ForJson JsonSingleton NoRoot
     pure emptySelect {selectFor = forJson, selectProjections = projections}
-  IR.MOutSinglerowObject singleRowField -> mkSelect JASSingleObject singleRowField
-  where
-    mkSelect jsonAggSelect annFields = do
-      let annSelect = IR.AnnSelectG annFields (IR.FromIdentifier withAlias) IR.noTablePermissions IR.noSelectArgs stringifyNum
-      V.runValidate (runFromIr $ mkSQLSelect jsonAggSelect annSelect) `onLeft` (throw500 . tshow)
+  IR.MOutSinglerowObject singleRowField -> mkSelect stringifyNum withAlias JASSingleObject singleRowField
 
-    -- SELECT COUNT(*) FROM [with_alias]
-    countSelect =
-      let countProjection = AggregateProjection $ Aliased (CountAggregate StarCountable) "count"
-       in emptySelect
-            { selectProjections = [countProjection],
-              selectFrom = Just $ TSQL.FromIdentifier withAlias
-            }
+mkSelect ::
+  MonadError QErr m =>
+  Bool ->
+  Text ->
+  JsonAggSelect ->
+  Fields (AnnFieldG 'MSSQL (Const Void) Expression) ->
+  m Select
+mkSelect stringifyNum withAlias jsonAggSelect annFields = do
+  let annSelect = IR.AnnSelectG annFields (IR.FromIdentifier withAlias) IR.noTablePermissions IR.noSelectArgs stringifyNum
+  V.runValidate (runFromIr $ mkSQLSelect jsonAggSelect annSelect) `onLeft` (throw500 . tshow)
 
-    textSelect t =
-      let textProjection = ExpressionProjection $ Aliased (ValueExpression (ODBC.TextValue t)) "exp"
-       in emptySelect {selectProjections = [textProjection]}
+-- SELECT COUNT(*) AS "count" FROM [with_alias]
+countSelect :: Text -> Select
+countSelect withAlias =
+  let countProjection = AggregateProjection $ Aliased (CountAggregate StarCountable) "count"
+   in emptySelect
+        { selectProjections = [countProjection],
+          selectFrom = Just $ TSQL.FromIdentifier withAlias
+        }
+
+-- SELECT '<text-value>' AS "exp"
+textSelect :: Text -> Select
+textSelect t =
+  let textProjection = ExpressionProjection $ Aliased (ValueExpression (ODBC.TextValue t)) "exp"
+   in emptySelect {selectProjections = [textProjection]}
 
 -- subscription
 

server/src-lib/Hasura/Backends/MSSQL/Instances/Schema.hs

@@ -35,7 +35,7 @@ instance BackendSchema 'MSSQL where
   buildTableRelayQueryFields = msBuildTableRelayQueryFields
   buildTableInsertMutationFields = msBuildTableInsertMutationFields
   buildTableUpdateMutationFields = msBuildTableUpdateMutationFields
-  buildTableDeleteMutationFields = msBuildTableDeleteMutationFields
+  buildTableDeleteMutationFields = GSB.buildTableDeleteMutationFields
   buildFunctionQueryFields = msBuildFunctionQueryFields
   buildFunctionRelayQueryFields = msBuildFunctionRelayQueryFields
   buildFunctionMutationFields = msBuildFunctionMutationFields

server/src-lib/Hasura/Backends/MSSQL/ToQuery.hs

@@ -10,6 +10,7 @@ module Hasura.Backends.MSSQL.ToQuery
     fromInsert,
     fromSetIdentityInsert,
     fromDelete,
+    fromSelectIntoTempTable,
     Printer (..),
   )
 where
@@ -189,8 +190,8 @@ fromSetValue = \case
   SetON -> "ON"
   SetOFF -> "OFF"
 
-fromSetIdentityInsert :: SetIdenityInsert -> Printer
-fromSetIdentityInsert SetIdenityInsert {..} =
+fromSetIdentityInsert :: SetIdentityInsert -> Printer
+fromSetIdentityInsert SetIdentityInsert {..} =
   SepByPrinter
     " "
     [ "SET IDENTITY_INSERT",
@@ -198,15 +199,71 @@ fromSetIdentityInsert SetIdenityInsert {..} =
       fromSetValue setValue
     ]
 
-fromDelete :: Delete -> Printer
-fromDelete Delete {deleteTable, deleteWhere} =
+-- | Generate a delete statement
+--
+-- > Delete
+-- >   (Aliased (TableName "table" "schema") "alias")
+-- >   [ColumnName "id", ColumnName "name"]
+-- >   (Where [OpExpression EQ' (ValueExpression (IntValue 1)) (ValueExpression (IntValue 1))])
+--
+-- Becomes:
+--
+-- > DELETE [alias] OUTPUT DELETED.[id], DELETED.[name] INTO #deleted([id], [name]) FROM [schema].[table] AS [alias] WHERE ((1) = (1))
+fromDelete :: TempTableName -> Delete -> Printer
+fromDelete tempTableName Delete {deleteTable, deleteColumns, deleteWhere} =
   SepByPrinter
     NewlinePrinter
     [ "DELETE " <+> fromNameText (aliasedAlias deleteTable),
+      "OUTPUT " <+> SepByPrinter ", " (map ((<+>) "DELETED." . fromColumnName) deleteColumns),
+      "INTO " <+> fromTempTableName tempTableName <+> parens (SepByPrinter ", " (map fromColumnName deleteColumns)),
       "FROM " <+> fromAliased (fmap fromTableName deleteTable),
       fromWhere deleteWhere
     ]
 
+-- | Converts `SelectIntoTempTable`.
+--
+--  > SelectIntoTempTable (TempTableName "deleted")  [UnifiedColumn "id" IntegerType, UnifiedColumn "name" TextType] (TableName "table" "schema")
+--
+--  Becomes:
+--
+--  > SELECT [id], [name] INTO #deleted([id], [name]) FROM [schema].[table] WHERE (1<>1) UNION ALL SELECT [id], [name] FROM [schema].[table];
+--
+--  We add the `UNION ALL` part to avoid copying identity constraints, and we cast columns with types such as `timestamp`
+--  which are non-insertable to a different type.
+fromSelectIntoTempTable :: SelectIntoTempTable -> Printer
+fromSelectIntoTempTable SelectIntoTempTable {sittTempTableName, sittColumns, sittFromTableName} =
+  SepByPrinter
+    NewlinePrinter
+    [ "SELECT "
+        <+> columns,
+      "INTO " <+> fromTempTableName sittTempTableName,
+      "FROM " <+> fromTableName sittFromTableName,
+      "WHERE " <+> falsePrinter,
+      "UNION ALL SELECT " <+> columns,
+      "FROM " <+> fromTableName sittFromTableName,
+      "WHERE " <+> falsePrinter
+    ]
+  where
+    -- column names separated by commas
+    columns =
+      SepByPrinter
+        ("," <+> NewlinePrinter)
+        (map columnNameFromUnifiedColumn sittColumns)
+
+    -- column name with potential modifications of types
+    columnNameFromUnifiedColumn (UnifiedColumn columnName columnType) =
+      case columnType of
+        -- The "timestamp" is type synonym for "rowversion" and it is just an incrementing number and does not preserve a date or a time.
+        -- So, the "timestamp" type is neither insertable nor explicitly updatable. Its values are unique binary numbers within a database.
+        -- We're using "binary" type instead so that we can copy a timestamp row value safely into the temporary table.
+        -- See https://docs.microsoft.com/en-us/sql/t-sql/data-types/rowversion-transact-sql for more details.
+        TimestampType -> "CAST(" <+> fromNameText columnName <+> " AS binary(8)) AS " <+> fromNameText columnName
+        _ -> fromNameText columnName
+
+-- | @TempTableName "deleted"@ becomes @\#deleted@
+fromTempTableName :: TempTableName -> Printer
+fromTempTableName (TempTableName v) = QueryPrinter (fromString . T.unpack $ "#" <> v)
+
 fromSelect :: Select -> Printer
 fromSelect Select {..} = fmap fromWith selectWith ?<+> wrapFor selectFor result
   where
@@ -438,6 +495,7 @@ fromFrom =
     FromOpenJson openJson -> fromAliased (fmap fromOpenJson openJson)
     FromSelect select -> fromAliased (fmap (parens . fromSelect) select)
     FromIdentifier identifier -> fromNameText identifier
+    FromTempTable aliasedTempTable -> fromAliased (fmap fromTempTableName aliasedTempTable)
 
 fromOpenJson :: OpenJson -> Printer
 fromOpenJson OpenJson {openJsonExpression, openJsonWith} =
@@ -482,6 +540,9 @@ fromAliased Aliased {..} =
   aliasedThing
     <+> ((" AS " <+>) . fromNameText) aliasedAlias
 
+fromColumnName :: ColumnName -> Printer
+fromColumnName (ColumnName colname) = fromNameText colname
+
 fromNameText :: Text -> Printer
 fromNameText t = QueryPrinter (rawUnescapedText ("[" <> t <> "]"))
 

server/src-lib/Hasura/Backends/MSSQL/Types/Instances.hs

@@ -41,7 +41,8 @@ $( fmap concat $ for
        ''UnifiedArrayRelationship,
        ''UnifiedUsing,
        ''UnifiedOn,
-       ''UnifiedColumn
+       ''UnifiedColumn,
+       ''TempTableName
      ]
      \name ->
        [d|
@@ -57,6 +58,8 @@ $( fmap concat $ for
 
          deriving instance Data $(conT name)
 
+         instance NFData $(conT name)
+
          instance FromJSON $(conT name)
 
          deriving instance Ord $(conT name)
@@ -92,7 +95,8 @@ $( fmap concat $ for
        ''OpenJson,
        ''JsonFieldSpec,
        ''Join,
-       ''JoinSource
+       ''JoinSource,
+       ''SelectIntoTempTable
      ]
      \name ->
        [d|

server/src-lib/Hasura/Backends/MSSQL/Types/Internal.hs

@@ -38,8 +38,10 @@ module Hasura.Backends.MSSQL.Types.Internal
     ScalarType (..),
     SchemaName (..),
     Select (..),
-    SetIdenityInsert (..),
+    SetIdentityInsert (..),
+    TempTableName (..),
     SetValue (..),
+    SelectIntoTempTable (..),
     SpatialOp (..),
     TableName (..),
     Top (..),
@@ -172,16 +174,28 @@ data SetValue
   = SetON
   | SetOFF
 
-data SetIdenityInsert = SetIdenityInsert
+data SetIdentityInsert = SetIdentityInsert
   { setTable :: !TableName,
     setValue :: !SetValue
   }
 
 data Delete = Delete
   { deleteTable :: !(Aliased TableName),
+    deleteColumns :: [ColumnName],
     deleteWhere :: !Where
   }
 
+-- | SELECT INTO temporary table statement without values.
+--   Used to create a temporary table with the same schema as an existing table.
+data SelectIntoTempTable = SelectIntoTempTable
+  { sittTempTableName :: TempTableName,
+    sittColumns :: [UnifiedColumn],
+    sittFromTableName :: TableName
+  }
+
+-- | A temporary table name is prepended by a hash-sign
+newtype TempTableName = TempTableName Text
+
 data Reselect = Reselect
   { reselectProjections :: ![Projection],
     reselectFor :: !For,
@@ -302,6 +316,7 @@ data From
   | FromOpenJson (Aliased OpenJson)
   | FromSelect (Aliased Select)
   | FromIdentifier Text
+  | FromTempTable (Aliased TempTableName)
 
 data OpenJson = OpenJson
   { openJsonExpression :: Expression,

server/src-lib/Hasura/RQL/IR/Delete.hs

@@ -1,3 +1,5 @@
+{-# LANGUAGE UndecidableInstances #-}
+
 module Hasura.RQL.IR.Delete
   ( AnnDel,
     AnnDelG (..),
@@ -21,3 +23,5 @@ data AnnDelG (b :: BackendType) (r :: BackendType -> Type) v = AnnDel
   deriving (Functor, Foldable, Traversable)
 
 type AnnDel b = AnnDelG b (Const Void) (SQLExpression b)
+
+deriving instance (Show (MutationOutputG b r a), Backend b, Show (BooleanOperators b a), Show a) => Show (AnnDelG b r a)

server/src-lib/Hasura/RQL/IR/Returning.hs

@@ -1,3 +1,5 @@
+{-# LANGUAGE UndecidableInstances #-}
+
 module Hasura.RQL.IR.Returning
   ( MutFld,
     MutFldG (..),
@@ -25,6 +27,8 @@ data MutFldG (b :: BackendType) (r :: BackendType -> Type) v
   | MRet !(AnnFieldsG b r v)
   deriving (Functor, Foldable, Traversable)
 
+deriving instance (Show (r b), Backend b, Show (BooleanOperators b a), Show a) => Show (MutFldG b r a)
+
 type MutFld b = MutFldG b (Const Void) (SQLExpression b)
 
 type MutFldsG b r v = Fields (MutFldG b r v)
@@ -34,6 +38,8 @@ data MutationOutputG (b :: BackendType) (r :: BackendType -> Type) v
   | MOutSinglerowObject !(AnnFieldsG b r v)
   deriving (Functor, Foldable, Traversable)
 
+deriving instance (Show (MutFldsG b r a), Show (r b), Backend b, Show (BooleanOperators b a), Show a) => Show (MutationOutputG b r a)
+
 type MutationOutput b = MutationOutputG b (Const Void) (SQLExpression b)
 
 type MutFlds b = MutFldsG b (Const Void) (SQLExpression b)

server/tests-py/context.py

@@ -786,6 +786,15 @@ class HGECtx:
             yml = yaml.YAML()
             return self.v1metadataq(yml.load(f))
 
+    def v1graphqlq(self, q, headers = {}):
+        return self.execute_query(q, "/v1/graphql", headers)
+
+    def v1graphql_f(self, fn):
+        with open(fn) as f:
+            # NOTE: preserve ordering with ruamel
+            yml = yaml.YAML()
+            return self.v1graphqlq(yml.load(f))
+
     def teardown(self):
         self.http.close()
         self.engine.dispose()

server/tests-py/queries/graphql_mutation/delete/basic/article_mssql.yaml

@@ -0,0 +1,16 @@
+description: Delete mutation on article
+url: /v1/graphql
+status: 200
+response:
+  data:
+    delete_article:
+      affected_rows: 1
+query:
+  query: |
+    mutation delete_article {
+      delete_article (
+        where: {id: {_eq: 2}}
+      ) {
+        affected_rows
+      }
+    }

server/tests-py/queries/graphql_mutation/delete/basic/author_returning_empty_articles_mssql.yaml

@@ -0,0 +1,27 @@
+description: Delete mutation on author with returning articles
+url: /v1/graphql
+status: 200
+response:
+  data:
+    delete_author:
+      affected_rows: 1
+      returning:
+      - id: 3
+        name: Author 3
+        articles: []
+query:
+  query: |
+    mutation DeleteAuthor3 {
+      delete_author(where: {id: {_eq: 3}}){
+        affected_rows
+        returning{
+          id
+          name
+          articles{
+            id
+            title
+            content
+          }
+        }
+      }
+    }

server/tests-py/queries/graphql_mutation/delete/basic/schema_setup_mssql.yaml

@@ -0,0 +1,159 @@
+type: bulk
+args:
+
+- type: mssql_run_sql
+  args:
+    source: mssql
+    sql: |
+
+      CREATE TABLE test_types
+      (
+          c1_smallint smallint,
+          c2_integer integer,
+          c3_bigint bigint,
+          c4_decimal decimal(5, 2),
+          c5_numeric numeric (4, 3),
+          c6_real real,
+          c7_double_precision double precision,
+          c11_varchar_3 varchar(3),
+          c12_char_4 char(4),
+          c13_text text,
+          c16_date date,
+          c17_time time,
+          c44_xml xml,
+          c45_money money,
+          c47_smallmoney smallmoney,
+          c48_bit bit,
+          c49_tinyint tinyint,
+          c50_float float,
+          c51_real real,
+          c52_datetime datetime,
+          c53_datetime2 datetime2,
+          c54_datetimeoffset datetimeoffset,
+          c55_smalldatetime smalldatetime,
+          c56_binary binary(4),
+          c57_varbinary varbinary(4),
+          c58_hierarchyid hierarchyid,
+          c59_uniqueidentifier uniqueidentifier
+      );
+
+      CREATE TABLE author
+      (
+          id int identity NOT NULL PRIMARY KEY,
+          name nvarchar(450) UNIQUE,
+          createdAt datetime
+      );
+
+      CREATE TABLE article
+      (
+          id int identity NOT NULL PRIMARY KEY,
+          title TEXT,
+          content TEXT,
+          is_published BIT,
+          published_on timestamp,
+          author_id int,
+          co_author_id int,
+          FOREIGN KEY (author_id) REFERENCES author(id),
+          FOREIGN KEY (co_author_id) REFERENCES author(id),
+      );
+
+      INSERT INTO test_types
+          (
+          c1_smallint,
+          c2_integer,
+          c3_bigint,
+          c4_decimal,
+          c5_numeric,
+          c6_real,
+          c7_double_precision,
+          c11_varchar_3,
+          c12_char_4,
+          c13_text,
+          c16_date,
+          c17_time,
+          c44_xml,
+          c45_money,
+          c47_smallmoney,
+          c48_bit,
+          c49_tinyint,
+          c50_float,
+          c51_real,
+          c52_datetime,
+          c53_datetime2,
+          c54_datetimeoffset,
+          c55_smalldatetime,
+          c56_binary,
+          c57_varbinary,
+          c58_hierarchyid,
+          c59_uniqueidentifier
+          )
+      VALUES
+          ( 3277 -- c1_smallint
+          , 2147483647 -- c2_integer
+          , 9223372036854775807 -- c3_bigint
+          , 123.45 -- c4_decimal
+          , 1.234 -- c5_numeric
+          , 0.00390625 -- c6_real
+          , 16.0001220703125 -- c7_double_precision
+          , 'abc' -- c11_varchar_3
+          , 'baaz' -- c12_char_4
+          , 'foo bar baz' -- c13_text
+          , '2014-09-14' -- c16_date
+          , '11:09:23' -- c17_time
+          , '<foo>bar</foo>' -- c44_xml
+          , 123.45 -- c45_money
+          , -123.45 -- c47_smallmoney
+          , 0 -- c48_bit
+          , 254 -- c49_tinyint
+          , -305.77 -- c50_float
+          , -36.82 -- c51_real
+          , '04-15-96 4am' -- c52_datetime
+          , '04-15-9999 23:59:59.9999999' -- c53_datetime2
+          , '2007-05-08 12:35:29.1234567 +12:15' -- c54_datetimeoffset
+          , '1955-12-13 12:43:10' -- c55_smalldatetime
+          , 0x0001e240 -- c56_binary
+          , 0x0001e240 -- c57_varbinary
+          , '/0.1/0.2/' -- c58_hierarchyid
+          , '0E984725-C51C-4BF4-9960-E1C80E27ABA0' -- c59_uniqueidentifier
+          );
+
+      INSERT INTO author
+          (name, createdAt)
+      VALUES
+          ('Author 1', '2017-09-21T09:39:44Z'),
+          ('Author 2', '2017-09-21T09:50:44Z'),
+          ('Author 3', '2017-09-21T09:55:44Z');
+
+      INSERT INTO article
+          (title, content, author_id, is_published)
+      VALUES
+          (
+              'Article 1',
+              'Sample article content 1',
+              1,
+              0
+              ),
+          (
+              'Article 2',
+              'Sample article content 2',
+              1,
+              1
+              ),
+          (
+              'Article 3',
+              'Sample article content 3',
+              1,
+              1
+              ),
+          (
+              'Article 4',
+              'Sample article content 4',
+              2,
+              1
+              ),
+          (
+              'Article 5',
+              'Sample article content 5',
+              2,
+              0
+              );

server/tests-py/queries/graphql_mutation/delete/basic/schema_teardown_mssql.yaml

@@ -0,0 +1,11 @@
+type: bulk
+args:
+
+- type: mssql_run_sql
+  args:
+    source: mssql
+    cascade: true
+    sql: |
+      drop table test_types;
+      drop table article;
+      drop table author;

server/tests-py/queries/graphql_mutation/delete/basic/setup_mssql.yaml

@@ -0,0 +1,40 @@
+type: bulk
+args:
+
+# track tables
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: test_types
+
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: author
+
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: article
+
+# create relationships
+- type: mssql_create_object_relationship
+  args:
+    source: mssql
+    table: article
+    name: author
+    using:
+      foreign_key_constraint_on: author_id
+
+- type: mssql_create_array_relationship
+  args:
+    source: mssql
+    table: author
+    name: articles
+    using:
+      foreign_key_constraint_on:
+        table: article
+        column: author_id

server/tests-py/queries/graphql_mutation/delete/basic/teardown_mssql.yaml

@@ -0,0 +1,24 @@
+type: bulk
+args:
+
+# untrack tables
+- type: mssql_untrack_table
+  args:
+    source: mssql
+    table:
+      name: test_types
+    cascade: true
+
+- type: mssql_untrack_table
+  args:
+    source: mssql
+    table:
+      name: article
+    cascade: true
+
+- type: mssql_untrack_table
+  args:
+    source: mssql
+    table:
+      name: author
+    cascade: true

server/tests-py/queries/graphql_mutation/delete/basic/test_types_mssql.yaml

@@ -0,0 +1,75 @@
+description: Delete mutation on test_types
+url: /v1/graphql
+status: 200
+response:
+  data:
+    delete_test_types:
+      affected_rows: 1
+      returning:
+      - c1_smallint: 3277
+        c2_integer: 2147483647
+        c3_bigint: 9223372036854775807
+        c4_decimal: 123.45
+        c5_numeric: 1.234
+        c6_real: 0.00390625
+        c7_double_precision: 16.0001220703125
+        c11_varchar_3: 'abc'
+        c12_char_4: 'baaz'
+        c13_text: 'foo bar baz'
+        c16_date: '2014-09-14'
+        c17_time: '11:09:23'
+        c44_xml: '<foo>bar</foo>'
+        c45_money: 123.45
+        c47_smallmoney: -123.45
+        c48_bit: 0
+        c49_tinyint: 254
+        c50_float: -305.77
+        c51_real: -36.82
+        c52_datetime: '1996-04-15T04:00:00'
+        c53_datetime2: '9999-04-15T23:59:59.9999999'
+        c54_datetimeoffset: '2007-05-08T12:35:29.1234567+12:15'
+        c55_smalldatetime: '1955-12-13T12:43:00'
+        c56_binary: AAHiQA==
+        c57_varbinary: AAHiQA==
+        c58_hierarchyid: '/0.1/0.2/'
+        c59_uniqueidentifier: '0E984725-C51C-4BF4-9960-E1C80E27ABA0'
+
+
+query:
+  query: |
+    mutation delete_test_types {
+      delete_test_types (
+        where: {c1_smallint: {_eq: 3277}}
+      ) {
+        affected_rows
+        returning {
+          c1_smallint
+          c2_integer
+          c3_bigint
+          c4_decimal
+          c5_numeric
+          c6_real
+          c7_double_precision
+          c11_varchar_3
+          c12_char_4
+          c13_text
+          c16_date
+          c17_time
+          c44_xml
+          c45_money
+          c47_smallmoney
+          c48_bit
+          c49_tinyint
+          c50_float
+          c51_real
+          c52_datetime
+          c53_datetime2
+          c54_datetimeoffset
+          c55_smalldatetime
+          c56_binary
+          c57_varbinary
+          c58_hierarchyid
+          c59_uniqueidentifier
+        }
+      }
+    }

server/tests-py/queries/graphql_mutation/delete/constraints/author_foreign_key_violation_mssql.yaml

@@ -0,0 +1,6 @@
+query: |
+  mutation {
+    delete_author(where: {id: {_eq: 2}}){
+      affected_rows
+    }
+  }

server/tests-py/queries/graphql_mutation/delete/constraints/schema_setup_mssql.yaml

@@ -0,0 +1,58 @@
+type: bulk
+args:
+
+- type: mssql_run_sql
+  args:
+    source: mssql
+    sql: |
+      create table author(
+          id INT IDENTITY NOT NULL PRIMARY KEY,
+          name NVARCHAR(450) UNIQUE
+      );
+      CREATE TABLE article (
+        id INT IDENTITY NOT NULL PRIMARY KEY,
+        title TEXT,
+        content TEXT,
+        is_published BIT,
+        author_id INTEGER NOT NULL REFERENCES author(id),
+        published_on TIMESTAMP
+      );
+
+      INSERT INTO author(name)
+      VALUES
+          ('Author 1'),
+          ('Author 2'),
+          ('Author 3');
+
+      INSERT INTO article(title, content, author_id, is_published)
+      VALUES
+          (
+              'Article 1',
+              'Sample article content 1',
+              1,
+              0
+              ),
+          (
+              'Article 2',
+              'Sample article content 2',
+              1,
+              1
+              ),
+          (
+              'Article 3',
+              'Sample article content 3',
+              1,
+              1
+              ),
+          (
+              'Article 4',
+              'Sample article content 4',
+              2,
+              1
+              ),
+          (
+              'Article 5',
+              'Sample article content 5',
+              2,
+              0
+              );

server/tests-py/queries/graphql_mutation/delete/constraints/schema_teardown_mssql.yaml

@@ -0,0 +1,9 @@
+type: bulk
+args:
+
+- type: mssql_run_sql
+  args:
+    source: mssql
+    sql: |
+      drop table article;
+      drop table author;

server/tests-py/queries/graphql_mutation/delete/constraints/setup_mssql.yaml

@@ -0,0 +1,36 @@
+type: bulk
+args:
+
+# Author table
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: author
+
+# Article table
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: article
+
+# Object relationship
+- type: mssql_create_object_relationship
+  args:
+    source: mssql
+    table: article
+    name: author
+    using:
+      foreign_key_constraint_on: author_id
+
+# Array relationship
+- type: mssql_create_array_relationship
+  args:
+    source: mssql
+    table: author
+    name: articles
+    using:
+      foreign_key_constraint_on:
+        table: article
+        column: author_id

server/tests-py/queries/graphql_mutation/delete/constraints/teardown_mssql.yaml

@@ -0,0 +1,24 @@
+type: bulk
+args:
+
+# Drop relationship first
+- type: mssql_drop_relationship
+  args:
+    source: mssql
+    relationship: articles
+    table:
+      name: author
+
+- type: mssql_untrack_table
+  args:
+    source: mssql
+    table:
+      name: article
+    cascade: true
+
+- type: mssql_untrack_table
+  args:
+    source: mssql
+    table:
+      name: author
+    cascade: true

server/tests-py/queries/graphql_mutation/delete/permissions/schema_setup_mssql.yaml

@@ -0,0 +1,78 @@
+type: bulk
+args:
+
+- type: mssql_run_sql
+  args:
+    source: mssql
+    sql: |
+      create table author(
+        id INT IDENTITY NOT NULL PRIMARY KEY,
+        name NVARCHAR(450) UNIQUE,
+        payments_done BIT NOT NULL DEFAULT 0,
+        user_id INT
+      );
+      CREATE TABLE article (
+        id INT IDENTITY NOT NULL PRIMARY KEY,
+        title TEXT,
+        content TEXT,
+        author_id INTEGER NOT NULL REFERENCES author(id),
+        is_published BIT,
+        published_on TIMESTAMP
+      );
+      CREATE TABLE resident (
+        id INT IDENTITY NOT NULL PRIMARY KEY,
+        name TEXT NOT NULL,
+        age INTEGER NOT NULL
+      );
+      create table "user" (
+        id INT IDENTITY NOT NULL PRIMARY KEY,
+        name NVARCHAR(450) UNIQUE,
+        is_admin BIT DEFAULT 0
+      );
+
+      create table account (
+        id INT IDENTITY NOT NULL PRIMARY KEY,
+        account_no INTEGER NOT NULL
+      );
+
+      insert into resident (name, age)
+        values
+          ('Griffin', 25),
+          ('Clarke', 26);
+
+      insert into author (name, payments_done)
+        values
+          ('Author 1', 0),
+          ('Author 2', 0),
+          ('Author 3', 1),
+          ('Author 4', 1),
+          ('Author 5', 1);
+
+      insert into article (content, title, author_id)
+        values
+          ( 'Sample article content 1',
+            'Article 1',
+            1
+          ),
+          ( 'Sample article content 2',
+            'Article 2',
+            1
+          ),
+          ( 'Sample article content 3',
+            'Article 3',
+            1
+          ),
+          ( 'Sample article content 4',
+            'Article 4',
+            2
+          ),
+          ( 'Sample article content 5',
+            'Article 5',
+            2
+          );
+
+      insert into "user" (name, is_admin)
+        values ('user_1', 0), ('user_2', 1)
+      ;
+
+      insert into account (account_no) values (1), (2) ;

server/tests-py/queries/graphql_mutation/delete/permissions/schema_teardown_mssql.yaml

@@ -0,0 +1,13 @@
+type: bulk
+args:
+
+- type: mssql_run_sql
+  args:
+    source: mssql
+    sql: |
+      drop table article;
+      drop table author;
+      drop table resident;
+      drop table "user";
+      drop table account;
+    cascade: true

server/tests-py/queries/graphql_mutation/delete/permissions/setup_mssql.yaml

@@ -0,0 +1,172 @@
+type: bulk
+args:
+
+# Author table
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: author
+
+# Article table
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: article
+
+
+# Object relationship
+- type: mssql_create_object_relationship
+  args:
+    source: mssql
+    table: article
+    name: author
+    using:
+      foreign_key_constraint_on: author_id
+
+# Array relationship
+- type: mssql_create_array_relationship
+  args:
+    source: mssql
+    table: author
+    name: articles
+    using:
+      foreign_key_constraint_on:
+        table: article
+        column: author_id
+
+# Prevent deletion if payments to the author is not yet done
+- type: mssql_create_delete_permission
+  args:
+    source: mssql
+    table: author
+    role: user
+    permission:
+      filter:
+        $and:
+          - id: X-HASURA-USER-ID
+          - payments_done:
+              _eq: 1
+
+# Author select permission for user
+- type: mssql_create_select_permission
+  args:
+    source: mssql
+    table: author
+    role: user
+    permission:
+      columns: [id, name, payments_done]
+      filter:
+        id: X-HASURA-USER-ID
+
+# A user can delete only his articles
+- type: mssql_create_select_permission
+  args:
+    source: mssql
+    table: article
+    role: user
+    permission:
+      columns:
+      - id
+      - title
+      - content
+      - author_id
+      filter:
+        $and:
+          - author_id: X-HASURA-USER-ID
+
+# A user can delete only his articles
+- type: mssql_create_delete_permission
+  args:
+    source: mssql
+    table: article
+    role: user
+    permission:
+      filter:
+        $and:
+          - author_id: X-HASURA-USER-ID
+
+# Create resident table
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: resident
+
+- type: mssql_create_delete_permission
+  args:
+    source: mssql
+    table: resident
+    role: resident
+    permission:
+      filter:
+        id: X-Hasura-Resident-Id
+
+- type: mssql_create_delete_permission
+  args:
+    source: mssql
+    table: resident
+    role: agent
+    permission:
+      filter:
+        id:
+          $in: X-Hasura-Allowed-Resident-Ids
+
+- type: mssql_create_select_permission
+  args:
+    source: mssql
+    table: resident
+    role: agent
+    permission:
+      columns:
+      - id
+      - name
+      - age
+      filter:
+        id:
+          $in: X-Hasura-Allowed-Resident-Ids
+
+# Tables to test '_exist' field
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: user
+
+- type: mssql_track_table
+  args:
+    source: mssql
+    table:
+      name: account
+
+- type: mssql_create_delete_permission
+  args:
+    source: mssql
+    table: account
+    role: user
+    permission:
+      filter:
+        _exists:
+          _table: user
+          _where:
+            id: X-Hasura-User-Id
+            is_admin:
+              _eq: 1
+
+- type: mssql_create_select_permission
+  args:
+    source: mssql
+    table: account
+    role: user
+    permission:
+      columns:
+      - id
+      - account_no
+      filter:
+        _exists:
+          _table: user
+          _where:
+            id: X-Hasura-User-Id
+            is_admin:
+              _eq: 1

server/tests-py/queries/graphql_mutation/delete/permissions/teardown_mssql.yaml

@@ -0,0 +1,16 @@
+type: bulk
+args:
+
+- type: mssql_drop_relationship
+  args:
+    source: mssql
+    relationship: author
+    table:
+      name: article
+
+- type: mssql_drop_relationship
+  args:
+    source: mssql
+    relationship: articles
+    table:
+      name: author

server/tests-py/queries/graphql_mutation/delete/permissions/user_delete_author.yaml

@@ -30,31 +30,3 @@
           }
         }
       }
-
-- description: Delete an author by pk
-  url: /v1/graphql
-  status: 200
-  headers:
-    X-Hasura-Role: user
-    X-Hasura-User-Id: '5'
-  response:
-    data:
-      delete_author_by_pk:
-        id: 5
-        name: Author 5
-        articles: []
-  query:
-    query: |
-      mutation {
-        delete_author_by_pk(
-          id: 5
-        ){
-          id
-          name
-          articles {
-            id
-            title
-            content
-          }
-        }
-      }

server/tests-py/queries/graphql_mutation/delete/permissions/user_delete_author_by_pk.yaml

@@ -0,0 +1,27 @@
+- description: Delete an author by pk
+  url: /v1/graphql
+  status: 200
+  headers:
+    X-Hasura-Role: user
+    X-Hasura-User-Id: '5'
+  response:
+    data:
+      delete_author_by_pk:
+        id: 5
+        name: Author 5
+        articles: []
+  query:
+    query: |
+      mutation {
+        delete_author_by_pk(
+          id: 5
+        ){
+          id
+          name
+          articles {
+            id
+            title
+            content
+          }
+        }
+      }

server/tests-py/test_graphql_mutations.py

@@ -539,6 +539,37 @@ class TestGraphqlDeleteBasic:
     def dir(cls):
         return "queries/graphql_mutation/delete/basic"
 
+@pytest.mark.parametrize("backend", ['mssql'])
+@pytest.mark.parametrize("transport", ['http', 'websocket'])
+@usefixtures('per_method_tests_db_state')
+class TestGraphqlDeleteBasicMSSQL:
+
+    def test_article_delete(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + "/article.yaml", transport)
+
+    def test_article_delete_returning(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + "/article_returning.yaml", transport)
+
+    def test_article_delete_returning_author(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + "/article_returning_author.yaml", transport)
+
+    def test_author_returning_empty_articles(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + "/author_returning_empty_articles_mssql.yaml", transport)
+
+    def test_article_by_pk(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + "/article_by_pk.yaml", transport)
+
+    def test_article_by_pk_null(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + "/article_by_pk_null.yaml", transport)
+
+    def test_test_types_delete(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + "/test_types_mssql.yaml", transport)
+
+
+    @classmethod
+    def dir(cls):
+        return "queries/graphql_mutation/delete/basic"
+
 @pytest.mark.parametrize("transport", ['http', 'websocket'])
 @use_mutation_fixtures
 class TestGraphqlDeleteConstraints:
@@ -550,6 +581,24 @@ class TestGraphqlDeleteConstraints:
     def dir(cls):
         return "queries/graphql_mutation/delete/constraints"
 
+@pytest.mark.parametrize("backend", ['mssql'])
+@pytest.mark.parametrize("transport", ['http', 'websocket'])
+@usefixtures('per_method_tests_db_state')
+class TestGraphqlDeleteConstraintsMSSQL:
+
+    # The response from this query is non-determinstic. It looks something like:
+    # `conflicted with the REFERENCE constraint "FK__article__author___1B29035F"`
+    # where 1B29035F changes with each call.
+    # This makes it hard to write an equality-based test for it, so we just check the error code.
+    def test_author_delete_foreign_key_violation(self, hge_ctx, transport):
+        st_code, resp = hge_ctx.v1graphql_f(self.dir() + '/author_foreign_key_violation_mssql.yaml')
+        assert st_code == 200, resp
+        assert len(resp['errors']) == 1, resp
+
+    @classmethod
+    def dir(cls):
+        return "queries/graphql_mutation/delete/constraints"
+
 
 @use_mutation_fixtures
 class TestGraphqlDeletePermissions:
@@ -572,15 +621,57 @@ class TestGraphqlDeletePermissions:
     def test_user_delete_author(self, hge_ctx):
         check_query_f(hge_ctx, self.dir() + "/user_delete_author.yaml")
 
+    def test_user_delete_author_by_pk(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/user_delete_author_by_pk.yaml")
+
     def test_user_delete_account_success(self, hge_ctx):
         check_query_f(hge_ctx, self.dir() + "/user_delete_account_success.yaml")
 
     def test_user_delete_account_no_rows(self, hge_ctx):
         check_query_f(hge_ctx, self.dir() + "/user_delete_account_no_rows.yaml")
+
     @classmethod
     def dir(cls):
         return "queries/graphql_mutation/delete/permissions"
 
+
+@pytest.mark.parametrize("backend", ['mssql'])
+@usefixtures('per_method_tests_db_state')
+class TestGraphqlDeletePermissionsMSSQL:
+
+    def test_author_can_delete_his_articles(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/author_can_delete_his_articles.yaml")
+
+    def test_author_cannot_delete_other_users_articles(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/author_cannot_delete_other_users_articles.yaml")
+
+    def test_resident_delete_without_select_perm_fail(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/resident_delete_without_select_perm_fail.yaml")
+
+    # array types for session values not supported
+    # def test_agent_delete_perm_arr_sess_var(self, hge_ctx):
+    #     check_query_f(hge_ctx, self.dir() + "/agent_delete_perm_arr_sess_var.yaml")
+
+    # def test_agent_delete_perm_arr_sess_var_fail(self, hge_ctx):
+    #     check_query_f(hge_ctx, self.dir() + "/agent_delete_perm_arr_sess_var_fail.yaml")
+
+    def test_user_delete_author(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/user_delete_author.yaml")
+
+    def test_user_delete_author_by_pk(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/user_delete_author_by_pk.yaml")
+
+    def test_user_delete_account_success(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/user_delete_account_success.yaml")
+
+    def test_user_delete_account_no_rows(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir() + "/user_delete_account_no_rows.yaml")
+
+    @classmethod
+    def dir(cls):
+        return "queries/graphql_mutation/delete/permissions"
+
+
 @pytest.mark.parametrize("transport", ['http', 'websocket'])
 @use_mutation_fixtures
 class TestGraphqlMutationCustomSchema:

server/tests-py/test_graphql_queries.py

@@ -306,6 +306,12 @@ class TestGraphQLQueryBasicCommon:
     def test_select_query_multiple_columns_obj_fkey(self, hge_ctx, transport):
         check_query_f(hge_ctx, self.dir() + "/select_multiple_columns_obj_fkey.yaml", transport)
 
+    def test_select_query_author_pk(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + '/select_query_author_by_pkey.yaml', transport)
+
+    def test_select_query_author_pk_null(self, hge_ctx, transport):
+        check_query_f(hge_ctx, self.dir() + '/select_query_author_by_pkey_null.yaml', transport)
+
     @classmethod
     def dir(cls):
         return 'queries/graphql_query/basic'