support view with column alias

Author: adrian-wang

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

@@ -380,7 +380,7 @@ private[hive] object HiveQl {
   protected def nameExpressions(exprs: Seq[Expression]): Seq[NamedExpression] = {
     exprs.zipWithIndex.map {
       case (ne: NamedExpression, _) => ne
-      case (e, i) => Alias(e, s"c_$i")()
+      case (e, i) => Alias(e, s"_c$i")()
     }
   }
 

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

@@ -281,7 +281,7 @@ private[hive] case class HiveGenericUdtf(
   }
 
   override protected def makeOutput() = {
-    // Use column names when given, otherwise c_1, c_2, ... c_n.
+    // Use column names when given, otherwise _c1, _c2, ... _cn.
     if (aliasNames.size == outputDataTypes.size) {
       aliasNames.zip(outputDataTypes).map {
         case (attrName, attrDataType) =>
@@ -290,7 +290,7 @@ private[hive] case class HiveGenericUdtf(
     } else {
       outputDataTypes.zipWithIndex.map {
         case (attrDataType, i) =>
-          AttributeReference(s"c_$i", attrDataType, nullable = true)()
+          AttributeReference(s"_c$i", attrDataType, nullable = true)()
       }
     }
   }