[CARBONDATA-2090] Fix the error message of alter streaming property

Fix the error message of alter streaming property

This closes #1873

integration/spark2/src/main/scala/org/apache/spark/sql/execution/strategy/DDLStrategy.scala

@@ -231,9 +231,14 @@ class DDLStrategy(sparkSession: SparkSession) extends SparkStrategy {
         // TODO remove this limitation later
         val property = properties.find(_._1.equalsIgnoreCase("streaming"))
         if (property.isDefined) {
-          if (!property.get._2.trim.equalsIgnoreCase("true")) {
+          if (carbonTable.isStreamingTable) {
             throw new MalformedCarbonCommandException(
               "Streaming property can not be changed once it is 'true'")
+          } else {
+            if (!property.get._2.trim.equalsIgnoreCase("true")) {
+              throw new MalformedCarbonCommandException(
+                "Streaming property value is incorrect")
+            }
           }
         }
         ExecutedCommandExec(CarbonAlterTableSetCommand(tableName, properties, isView)) :: Nil

integration/spark2/src/test/scala/org/apache/spark/carbondata/TestStreamingTableOperation.scala

@@ -181,7 +181,11 @@ class TestStreamingTableOperation extends QueryTest with BeforeAndAfterAll {
   }
 
   // normal table not support streaming ingest
-  test("normal table not support streaming ingest") {
+  test("normal table not support streaming ingest and alter normal table's streaming property") {
+    // alter normal table's streaming property
+    val msg = intercept[MalformedCarbonCommandException](sql("alter table streaming.batch_table set tblproperties('streaming'='false')"))
+    assertResult("Streaming property value is incorrect")(msg.getMessage)
+
     val identifier = new TableIdentifier("batch_table", Option("streaming"))
     val carbonTable = CarbonEnv.getInstance(spark).carbonMetastore.lookupRelation(identifier)(spark)
       .asInstanceOf[CarbonRelation].metaData.carbonTable
@@ -518,6 +522,11 @@ class TestStreamingTableOperation extends QueryTest with BeforeAndAfterAll {
       case _ =>
         assert(false, "should support set table to streaming")
     }
+
+    // alter streaming table's streaming property
+    val msg = intercept[MalformedCarbonCommandException](sql("alter table streaming.stream_table_handoff set tblproperties('streaming'='false')"))
+    assertResult("Streaming property can not be changed once it is 'true'")(msg.getMessage)
+
     val segments = sql("show segments for table streaming.stream_table_handoff").collect()
     assert(segments.length == 2 || segments.length == 3)
     assertResult("Streaming")(segments(0).getString(1))