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https://github.com/hasura/graphql-engine.git
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92ab93775f
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3856 GitOrigin-RevId: 8527749c33df1a5bdde29338630714e673e308ab
236 lines
11 KiB
Haskell
236 lines
11 KiB
Haskell
{-# OPTIONS_HADDOCK ignore-exports #-}
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-- | Responsible for translating and building an MSSQL execution plan for
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-- delete mutations.
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--
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-- This module is used by "Hasura.Backends.MSSQL.Instances.Execute".
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module Hasura.Backends.MSSQL.Execute.Insert
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( executeInsert,
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)
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where
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import Data.HashMap.Strict qualified as HM
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import Database.MSSQL.Transaction qualified as Tx
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import Hasura.Backends.MSSQL.Connection
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import Hasura.Backends.MSSQL.FromIr as TSQL
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import Hasura.Backends.MSSQL.FromIr.Constants (tempTableNameInserted, tempTableNameValues)
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import Hasura.Backends.MSSQL.FromIr.Expression
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import Hasura.Backends.MSSQL.FromIr.Insert (toMerge)
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import Hasura.Backends.MSSQL.FromIr.Insert qualified as TSQL
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import Hasura.Backends.MSSQL.FromIr.MutationResponse
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import Hasura.Backends.MSSQL.FromIr.SelectIntoTempTable qualified as TSQL
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import Hasura.Backends.MSSQL.Plan
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import Hasura.Backends.MSSQL.SQL.Error
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import Hasura.Backends.MSSQL.ToQuery as TQ
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import Hasura.Backends.MSSQL.Types.Insert (BackendInsert (..), IfMatched)
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import Hasura.Backends.MSSQL.Types.Internal as TSQL
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import Hasura.Base.Error
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import Hasura.EncJSON
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import Hasura.GraphQL.Parser
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import Hasura.Prelude
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import Hasura.RQL.IR
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import Hasura.RQL.Types
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import Hasura.Session
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-- | Execute and insert/upsert mutation against MS SQL Server.
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-- See the documentation for 'buildInsertTx' to see how it's done.
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executeInsert ::
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MonadError QErr m =>
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UserInfo ->
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StringifyNumbers ->
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SourceConfig 'MSSQL ->
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AnnInsert 'MSSQL Void (UnpreparedValue 'MSSQL) ->
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m (ExceptT QErr IO EncJSON)
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executeInsert userInfo stringifyNum sourceConfig annInsert = do
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-- Convert the leaf values from @'UnpreparedValue' to sql @'Expression'
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insert <- traverse (prepareValueQuery sessionVariables) annInsert
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let insertTx = buildInsertTx tableName withAlias stringifyNum insert
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pure $ mssqlRunReadWrite (_mscExecCtx sourceConfig) insertTx
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where
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sessionVariables = _uiSession userInfo
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tableName = _aiTableName $ _aiData annInsert
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withAlias = "with_alias"
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-- | Translates an IR Insert/upsert mutation description to SQL and
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-- builds a corresponding transaction to run against MS SQL Server.
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--
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-- Execution of a MSSQL insert mutation broadly involves two steps.
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--
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-- > insert_table(objects: [
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-- > {column1: value1, column2: value2},
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-- > {column1: value3, column2: value4}
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-- > ],
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-- > if_matched: {match_columns: [column1], update_columns: [column2]} # Optional field to enable upserting
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-- > ){
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-- > affected_rows
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-- > returning {
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-- > column1
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-- > column2
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-- > }
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-- > }
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--
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-- = Step 1: Inserting rows into the table
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--
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-- a. Create an empty temporary table with name #inserted to store affected rows (for the response)
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--
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-- > SELECT column1, column2 INTO #inserted FROM some_table WHERE (1 <> 1)
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-- > UNION ALL SELECT column1, column2 FROM some_table WHERE (1 <> 1);
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--
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-- b. If 'if_matched' is found: Use MERGE statment to perform upsert
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--
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-- b.1 Use #values temporary table to store input object values
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--
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-- > SELECT column1, column2 INTO #values FROM some_table WHERE (1 <> 1)
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--
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-- b.2 Insert input object values into the temporary table
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--
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-- > INSERT INTO #values (column1, column2) VALUES (value1, value2), (value3, value4)
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--
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--
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-- b.3 Generate an SQL Merge statement to perform either update or insert (upsert) to the table
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--
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-- > MERGE some_table AS [target]
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-- > USING (SELECT column1, column2 from #values) AS [source](column1, column2) ON ([target].column1 = [source].column1)
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-- > WHEN MATCHED THEN UPDATE SET [column2] = [source].[column2]
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-- > WHEN NOT MATCHED THEN INSERT (column1, column2) VALUES ([source].column1, [source].column2)
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-- > OUTPUT INSERTED.column1, INSERTED.column2 INTO #inserted(column1, column2)
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--
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-- __NOTE__: In @MERGE@ statement, we use @SELECT query from a temporary table@ as source but not @VALUES@ expression
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-- because, we can't use @DEFAULT@ expression (for missing columns in @objects@ field) in @VALUES@ expression.
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--
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-- __else__: Generate an SQL Insert statement from the GraphQL insert mutation with OUTPUT expression to fill @#inserted@ temporary table with inserted rows
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--
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-- > INSERT INTO some_table (column1, column2) OUTPUT INSERTED.column1, INSERTED.column2 INTO #inserted(column1, column2) VALUES (value1, value2), (value3, value4);
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--
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-- = Step 2: Generation of the mutation response
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--
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-- An SQL statement is generated and when executed it returns the mutation selection set containing 'affected_rows' and 'returning' field values.
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-- The statement is generated with multiple sub select queries explained below:
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--
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-- a. A SQL Select statement to fetch only inserted rows from temporary table
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--
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-- > <table_select> := SELECT * FROM #inserted
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--
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-- The above select statement is referred through a common table expression - @WITH [with_alias] AS (<table_select>)@
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--
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-- b. The @affected_rows@ field value is obtained by using @COUNT@ aggregation and the @returning@ field selection set is translated to
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-- a SQL select statement using 'mkSQLSelect'.
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--
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-- > <mutation_output_select> :=
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-- > SELECT (SELECT COUNT(*) FROM [with_alias]) AS [affected_rows], (select_from_returning) AS [returning]
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-- > FOR JSON PATH, INCLUDE_NULL_VALUES, WITHOUT_ARRAY_WRAPPER
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--
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-- c. Evaluate the check constraint using @CASE@ expression. We use @SUM@ aggregation to check if any inserted row has failed the check constraint.
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--
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-- > <check_constraint_select> :=
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-- > SELECT SUM(CASE WHEN <check_boolean_expression> THEN 0 ELSE 1 END)
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-- > FROM [with_alias]
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--
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-- d. The final select statement look like
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--
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-- > WITH "with_alias" AS (<table_select>)
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-- > SELECT (<mutation_output_select>) AS [mutation_response], (<check_constraint_select>) AS [check_constraint_select]
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--
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-- When executed, the above statement returns a single row with mutation response as a string value and check constraint result as an integer value.
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buildInsertTx :: TSQL.TableName -> Text -> StringifyNumbers -> AnnInsert 'MSSQL Void Expression -> Tx.TxET QErr IO EncJSON
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buildInsertTx tableName withAlias stringifyNum insert = do
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let tableColumns = _aiTableCols $ _aiData insert
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ifMatchedField = _biIfMatched . _aiBackendInsert . _aiData $ insert
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-- Create #inserted temporary table
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let createInsertedTempTableQuery =
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toQueryFlat $
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TQ.fromSelectIntoTempTable $
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TSQL.toSelectIntoTempTable tempTableNameInserted tableName tableColumns RemoveConstraints
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Tx.unitQueryE defaultMSSQLTxErrorHandler createInsertedTempTableQuery
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-- Choose between running a regular @INSERT INTO@ statement or a @MERGE@ statement
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-- depending on the @if_matched@ field.
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--
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-- Affected rows will be inserted into the #inserted temporary table regardless.
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case ifMatchedField of
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Nothing -> do
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-- Insert values into the table using INSERT query
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let insertQuery = toQueryFlat $ TQ.fromInsert $ TSQL.fromInsert insert
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Tx.unitQueryE mutationMSSQLTxErrorHandler insertQuery
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Just ifMatched -> buildUpsertTx tableName insert ifMatched
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-- Build a response to the user using the values in the temporary table named #inserted
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(responseText, checkConditionInt) <- buildInsertResponseTx stringifyNum withAlias insert
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-- Drop the #inserted temp table
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Tx.unitQueryE defaultMSSQLTxErrorHandler $ toQueryFlat $ dropTempTableQuery tempTableNameInserted
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-- Raise an exception if the check condition is not met
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unless (checkConditionInt == 0) $
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throw400 PermissionError "check constraint of an insert permission has failed"
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pure $ encJFromText responseText
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-- | Translates an IR IfMatched clause to SQL and
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-- builds a corresponding transaction to run against MS SQL Server.
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--
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-- We do this in 2 steps:
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--
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-- 1. Create a temporary table called @#values@ which will hold the values the user want to insert,
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-- and insert the values into it
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-- 2. Build an run a @MERGE@ statement to either insert or upsert the values from the temporary table @#values@
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-- into the original table, and output the affected rows into another temporary table called @#inserted@
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-- which will be used to build a "response" for the user.
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--
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-- Should be used as part of a bigger transaction in 'buildInsertTx'.
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buildUpsertTx :: TSQL.TableName -> AnnInsert 'MSSQL Void Expression -> IfMatched Expression -> Tx.TxET QErr IO ()
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buildUpsertTx tableName insert ifMatched = do
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let presets = _aiDefVals $ _aiData insert
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insertColumnNames =
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concatMap (map fst . getInsertColumns) (_aiInsObj $ _aiData insert) <> HM.keys presets
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allTableColumns = _aiTableCols $ _aiData insert
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insertColumns = filter (\c -> ciColumn c `elem` insertColumnNames) allTableColumns
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createValuesTempTableQuery =
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toQueryFlat $
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TQ.fromSelectIntoTempTable $
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-- We want to KeepConstraints here so the user can omit values for identity columns such as `id`
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TSQL.toSelectIntoTempTable tempTableNameValues tableName insertColumns KeepConstraints
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-- Create #values temporary table
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Tx.unitQueryE defaultMSSQLTxErrorHandler createValuesTempTableQuery
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-- Store values in #values temporary table
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let insertValuesIntoTempTableQuery =
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toQueryFlat $
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TQ.fromInsertValuesIntoTempTable $
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TSQL.toInsertValuesIntoTempTable tempTableNameValues insert
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Tx.unitQueryE mutationMSSQLTxErrorHandler insertValuesIntoTempTableQuery
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-- Run the MERGE query and store the mutated rows in #inserted temporary table
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merge <- runFromIr (toMerge tableName (_aiInsObj $ _aiData insert) allTableColumns ifMatched)
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let mergeQuery = toQueryFlat $ TQ.fromMerge merge
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Tx.unitQueryE mutationMSSQLTxErrorHandler mergeQuery
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-- After @MERGE@ we no longer need this temporary table
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Tx.unitQueryE defaultMSSQLTxErrorHandler $ toQueryFlat $ dropTempTableQuery tempTableNameValues
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-- | Builds a response to the user using the values in the temporary table named #inserted.
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buildInsertResponseTx :: StringifyNumbers -> Text -> AnnInsert 'MSSQL Void Expression -> Tx.TxET QErr IO (Text, Int)
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buildInsertResponseTx stringifyNum withAlias insert = do
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-- Generate a SQL SELECT statement which outputs the mutation response using the #inserted
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mutationOutputSelect <- runFromIr $ mkMutationOutputSelect stringifyNum withAlias $ _aiOutput insert
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-- The check constraint is translated to boolean expression
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let checkCondition = fst $ _aiCheckCond $ _aiData insert
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checkBoolExp <- runFromIr $ runReaderT (fromGBoolExp checkCondition) (EntityAlias withAlias)
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let withSelect =
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emptySelect
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{ selectProjections = [StarProjection],
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selectFrom = Just $ FromTempTable $ Aliased tempTableNameInserted "inserted_alias"
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}
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-- SELECT (<mutation_output_select>) AS [mutation_response], (<check_constraint_select>) AS [check_constraint_select]
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mutationOutputCheckConstraintSelect = selectMutationOutputAndCheckCondition withAlias mutationOutputSelect checkBoolExp
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-- WITH "with_alias" AS (<table_select>)
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-- SELECT (<mutation_output_select>) AS [mutation_response], (<check_constraint_select>) AS [check_constraint_select]
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finalSelect = mutationOutputCheckConstraintSelect {selectWith = Just $ With $ pure $ Aliased withSelect withAlias}
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-- Execute SELECT query to fetch mutation response and check constraint result
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Tx.singleRowQueryE defaultMSSQLTxErrorHandler (toQueryFlat $ TQ.fromSelect finalSelect)
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