andrej-db commented on code in PR #48621:
URL: https://github.com/apache/spark/pull/48621#discussion_r1814554194
##########
sql/core/src/main/scala/org/apache/spark/sql/jdbc/MsSqlServerDialect.scala:
##########
@@ -88,11 +88,31 @@ private case class MsSqlServerDialect() extends JdbcDialect
with NoLegacyJDBCErr
case e: Predicate => e.name() match {
case "=" | "<>" | "<=>" | "<" | "<=" | ">" | ">=" =>
val Array(l, r) = e.children().map {
- case p: Predicate => s"CASE WHEN ${inputToSQL(p)} THEN 1 ELSE 0
END"
+ case p: Predicate => inputToCaseWhenSQL(p)
case o => inputToSQL(o)
}
visitBinaryComparison(e.name(), l, r)
- case "CASE_WHEN" =>
visitCaseWhen(expressionsToStringArray(e.children())) + " = 1"
+ case "CASE_WHEN" =>
+ // Since MsSqlServer cannot handle boolean expressions inside
+ // a CASE WHEN, it is necessary to convert those to another
+ // CASE WHEN expression that will return 1 or 0 depending on
+ // the result. Exceptions are TRUE and FALSE, which already
+ // get translated to 1 and 0.
+ // Example:
+ // In: ... CASE WHEN a = b THEN c = d ... END
+ // Out: ... CASE WHEN a = b THEN CASE WHEN c = d THEN 1 ELSE 0 END
... END = 1
Review Comment:
perhaps, it might be cleaner for the end user
##########
sql/core/src/main/scala/org/apache/spark/sql/jdbc/MsSqlServerDialect.scala:
##########
@@ -88,11 +88,31 @@ private case class MsSqlServerDialect() extends JdbcDialect
with NoLegacyJDBCErr
case e: Predicate => e.name() match {
case "=" | "<>" | "<=>" | "<" | "<=" | ">" | ">=" =>
val Array(l, r) = e.children().map {
- case p: Predicate => s"CASE WHEN ${inputToSQL(p)} THEN 1 ELSE 0
END"
+ case p: Predicate => inputToCaseWhenSQL(p)
case o => inputToSQL(o)
}
visitBinaryComparison(e.name(), l, r)
- case "CASE_WHEN" =>
visitCaseWhen(expressionsToStringArray(e.children())) + " = 1"
+ case "CASE_WHEN" =>
+ // Since MsSqlServer cannot handle boolean expressions inside
+ // a CASE WHEN, it is necessary to convert those to another
+ // CASE WHEN expression that will return 1 or 0 depending on
+ // the result. Exceptions are TRUE and FALSE, which already
+ // get translated to 1 and 0.
+ // Example:
+ // In: ... CASE WHEN a = b THEN c = d ... END
+ // Out: ... CASE WHEN a = b THEN CASE WHEN c = d THEN 1 ELSE 0 END
... END = 1
Review Comment:
your call
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