![]() Sometimes you want to have additional data for each relationship. "Name" ) = ( ? ) END ) - With values: Many-to-many with arbitrary data "Name" ) IS NULL ) OR (( ? ) IS NULL ) THEN ? ELSE ( "t0". "Name" ) IS NULL ) AND (( ? ) IS NULL ) THEN ? WHEN (( "t0". "UnitPrice" AS "res10" FROM "Playlist" AS "t0" INNER JOIN "Track" AS "t1" INNER JOIN "PlaylistTrack" AS "t2" ON (( "t2". For example, to get all tracks from the playlists named The Chinook database associates multiple tracks with a playlist via the With those of right through joinThrough and return the results of left and Key of left and right from joinThrough, associate all entries of left This reads: for any database db tables joinThrough, left, and right Īnd sane select syntax syntax, where the primary keys of left and rightĪre comparable as value expressions and we have some way of extracting a primary ManyToMany_ :: ( Database be db, Table joinThrough, Table left, Table right, Sql92SelectSanit圜heck syntax, IsSql92SelectSyntax syntax, SqlEq ( QExpr ( Sql92SelectExpressionSyntax syntax ) s ) ( PrimaryKey left ( QExpr ( Sql92SelectExpressionSyntax syntax ) s )), SqlEq ( QExpr ( Sql92SelectExpressionSyntax syntax ) s ) ( PrimaryKey right ( QExpr ( Sql92SelectExpressionSyntax syntax ) s )) ) => DatabaseEntity be db ( TableEntity joinThrough ) -> ( joinThrough ( QExpr ( Sql92SelectExpressionSyntax syntax ) s ) -> PrimaryKey left ( QExpr ( Sql92SelectExpressionSyntax syntax ) s )) -> ( joinThrough ( QExpr ( Sql92SelectExpressionSyntax syntax ) s ) -> PrimaryKey right ( QExpr ( Sql92SelectExpressionSyntax syntax ) s )) -> Q syntax db s ( left ( QExpr ( Sql92SelectExpressionSyntax syntax ) s )) -> Q syntax db s ( right ( QExpr ( Sql92SelectExpressionSyntax syntax ) s )) -> Q syntax db s ( left ( QExpr ( Sql92SelectExpressionSyntax syntax ) s ), right ( QExpr ( Sql92SelectExpressionSyntax syntax ) s )) InvoiceLine for each Invoice, use the oneToMany_ combinator. Important to understand that joining is fundamental to the structure of the Qīeam supports querying for one-to-many joins. Most users will use the methods below to express JOINs, but it is nevertheless To express joins which more closely reflect the underlying SQL. Some backends are more temperamental, so Beam offers several more idiomatic ways Rather than the ON clause, This is fine for most inner joins on most databaseĮngines, as the query optimizer will execute both queries similarly. ![]() Note that beam has floated the guard_ expression into the WHERE clause, "Quantity" AS "res13" FROM "Invoice" AS "t0" INNER JOIN "InvoiceLine" AS "t1" WHERE ( "t1". ![]()
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