[SPARK-3834][SQL] Backticks not correctly handled in subquery aliases

The queries like SELECT a.key FROM (SELECT key FROM src) \`a\` does not work as backticks in subquery aliases are not handled properly. This PR fixes that.

Author : ravipesala ravindra.pesalahuawei.com

Author: ravipesala <[email protected]>

Closes apache#2737 from ravipesala/SPARK-3834 and squashes the following commits:

0e0ab98 [ravipesala] Fixing issue in backtick handling for subquery aliases

Conflicts:
	sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala

Author: ravipesala

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala

@@ -658,7 +658,7 @@ private[hive] object HiveQl {
   def nodeToRelation(node: Node): LogicalPlan = node match {
     case Token("TOK_SUBQUERY",
            query :: Token(alias, Nil) :: Nil) =>
-      Subquery(alias, nodeToPlan(query))
+      Subquery(cleanIdentifier(alias), nodeToPlan(query))
 
     case Token(laterViewToken(isOuter), selectClause :: relationClause :: Nil) =>
       val Token("TOK_SELECT",

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala

@@ -47,4 +47,30 @@ class SQLQuerySuite extends QueryTest {
           GROUP BY key, value
           ORDER BY value) a""").collect().toSeq)
   }
+
+  test("double nested data") {
+    sparkContext.parallelize(Nested1(Nested2(Nested3(1))) :: Nil).registerTempTable("nested")
+    checkAnswer(
+      sql("SELECT f1.f2.f3 FROM nested"),
+      1)
+  }
+
+  test("test CTAS") {
+    checkAnswer(sql("CREATE TABLE test_ctas_123 AS SELECT key, value FROM src"), Seq.empty[Row])
+    checkAnswer(
+      sql("SELECT key, value FROM test_ctas_123 ORDER BY key"), 
+      sql("SELECT key, value FROM src ORDER BY key").collect().toSeq)
+  }
+
+  test("SPARK-3708 Backticks aren't handled correctly is aliases") {
+    checkAnswer(
+      sql("SELECT k FROM (SELECT `key` AS `k` FROM src) a"),
+      sql("SELECT `key` FROM src").collect().toSeq)
+  }
+
+  test("SPARK-3834 Backticks not correctly handled in subquery aliases") {
+    checkAnswer(
+      sql("SELECT a.key FROM (SELECT key FROM src) `a`"),
+      sql("SELECT `key` FROM src").collect().toSeq)
+  }
 }