[SPARK-16457][SQL] Fix Wrong Messages when CTAS with a Partition By Clause

#### What changes were proposed in this pull request?
When doing a CTAS with a Partition By clause, we got a wrong error message.

For example,
```SQL
CREATE TABLE gen__tmp
PARTITIONED BY (key string)
AS SELECT key, value FROM mytable1
```
The error message we get now is like
```
Operation not allowed: Schema may not be specified in a Create Table As Select (CTAS) statement(line 2, pos 0)
```

However, based on the code, the message we should get is like
```
Operation not allowed: A Create Table As Select (CTAS) statement is not allowed to create a partitioned table using Hive's file formats. Please use the syntax of "CREATE TABLE tableName USING dataSource OPTIONS (...) PARTITIONED BY ...\" to create a partitioned table through a CTAS statement.(line 2, pos 0)
```

Currently, partitioning columns is part of the schema. This PR fixes the bug by changing the detection orders.

#### How was this patch tested?
Added test cases.

Author: gatorsmile <gatorsmile@gmail.com>

Closes #14113 from gatorsmile/ctas.

1 files changed, 6 insertions, 6 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala
index 2bb686254c..c3e3b215bb 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala
@@ -998,12 +998,6 @@ class SparkSqlAstBuilder(conf: SQLConf) extends AstBuilder {
 
     selectQuery match {
       case Some(q) =>
-        // Just use whatever is projected in the select statement as our schema
-        if (schema.nonEmpty) {
-          operationNotAllowed(
-            "Schema may not be specified in a Create Table As Select (CTAS) statement",
-            ctx)
-        }
         // Hive does not allow to use a CTAS statement to create a partitioned table.
         if (tableDesc.partitionColumnNames.nonEmpty) {
           val errorMessage = "A Create Table As Select (CTAS) statement is not allowed to " +
@@ -1013,6 +1007,12 @@ class SparkSqlAstBuilder(conf: SQLConf) extends AstBuilder {
             "CTAS statement."
           operationNotAllowed(errorMessage, ctx)
         }
+        // Just use whatever is projected in the select statement as our schema
+        if (schema.nonEmpty) {
+          operationNotAllowed(
+            "Schema may not be specified in a Create Table As Select (CTAS) statement",
+            ctx)
+        }
 
         val hasStorageProperties = (ctx.createFileFormat != null) || (ctx.rowFormat != null)
         if (conf.convertCTAS && !hasStorageProperties) {