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relational-query: expand column expression of case clause.

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(grafted from d4f07e53346583b47530e0fa6fa59273219085d9)
This commit is contained in:
Kei Hibino 2017-05-07 21:50:02 +09:00
parent 3cd3ed2eb3
commit f3db0df120
1 changed files with 17 additions and 0 deletions
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17
relational-query/src/Database/Relational/Query/Sub.hs
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@ -58,6 +58,7 @@ import Database.Relational.Query.Internal.GroupingSQL
(AggregateElem, composeGroupBy, )
import Database.Relational.Query.Internal.Sub
(SubQuery (..), Projection,
CaseClause(..), WhenClauses (..),
UntypedProjection, ProjectionUnit (..),
JoinProduct, QueryProductTree, ProductBuilder,
NodeAttr (Just', Maybe), ProductTree (Leaf, Join),
@ -243,12 +244,28 @@ untypedProjectionFromJoinedSubQuery qs = d $ Internal.unQualify qs where
d (Flat {}) = normalized
d (Aggregated {}) = normalized
-- | index result of each when clause and else clause.
indexWhensClause :: WhenClauses -> Int -> StringSQL
indexWhensClause (WhenClauses ps e) i =
mconcat [ when' p r | (p, r) <- ps] <> else' <> SQL.END
where
when' p r = SQL.WHEN <> rowStringSQL (map columnOfProjectionUnit p) <>
SQL.THEN <> columnOfUntypedProjection r i
else' = SQL.ELSE <> columnOfUntypedProjection e i
-- | index result of each when clause and else clause.
caseClause :: CaseClause -> Int -> StringSQL
caseClause c i = d c where
d (CaseSearch wcl) = SQL.CASE <> indexWhensClause wcl i
d (CaseSimple m wcl) = SQL.CASE <> rowStringSQL (map columnOfProjectionUnit m) <> indexWhensClause wcl i
-- | Convert from ProjectionUnit into column.
columnOfProjectionUnit :: ProjectionUnit -> StringSQL
columnOfProjectionUnit = d where
d (RawColumn e) = e
d (SubQueryRef qi) = Internal.qualifier qi `columnFromId` Internal.unQualify qi
d (Scalar sub) = showUnitSQL sub
d (Case c i) = caseClause c i
-- | Get column SQL string of 'UntypedProjection'.
columnOfUntypedProjection :: UntypedProjection -- ^ Source 'Projection'