[GitHub] [spark] beliefer commented on a diff in pull request #39667: [SPARK-42131][SQL] Extract the function that construct the select statement for JDBC dialect.

["beliefer (via GitHub)" <gi...@apache.org>]

beliefer commented on code in PR #39667:
URL: https://github.com/apache/spark/pull/39667#discussion_r1093932998


##########
sql/core/src/main/scala/org/apache/spark/sql/jdbc/MsSqlServerDialect.scala:
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@@ -63,6 +64,20 @@ private object MsSqlServerDialect extends JdbcDialect {
     supportedFunctions.contains(funcName)
 
   class MsSqlServerSQLBuilder extends JDBCSQLBuilder {
+    override def visitSortOrder(
+        sortKey: String, sortDirection: SortDirection, nullOrdering: NullOrdering): String = {
+      (sortDirection, nullOrdering) match {
+        case (SortDirection.ASCENDING, NullOrdering.NULLS_FIRST) =>
+          s"$sortKey $sortDirection"
+        case (SortDirection.ASCENDING, NullOrdering.NULLS_LAST) =>
+          s"CASE WHEN $sortKey IS NULL THEN 1 ELSE 0 END, $sortKey $sortDirection"

Review Comment:
   It's not a standard way and just is a little skill.



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