andrej-db commented on code in PR #48621:
URL: https://github.com/apache/spark/pull/48621#discussion_r1816733357
##########
sql/core/src/main/scala/org/apache/spark/sql/jdbc/MsSqlServerDialect.scala:
##########
@@ -88,11 +88,29 @@ 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 an IIF
+ // expression that will return 1 or 0 depending on the result.
+ // Example:
+ // In: ... CASE WHEN a = b THEN c = d ...
+ // Out: ... CASE WHEN a = b THEN IIF(c = d, 1, 0) ...
+
+ // grouped turns Array[Expression] to Array[Array[Expression]]
+ // with a len of max 2 (final one will have only one)
+ val stringArray = e.children().grouped(2).flatMap { arr =>
+ arr.dropRight(1).map(inputToSQL) :+
+ (arr.last match {
+ case p: Predicate if p.name() != "ALWAYS_TRUE" && p.name()
!= "ALWAYS_FALSE" =>
Review Comment:
problem is that MsSql cannot ask for a boolean as it cannot handle booleans.
Any other DB will know how to translate it so we are ok. Only way this poses a
problem is if we say CASE WHEN TRUE THEN which makes no sense so we are good
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
