Github user wuchong commented on a diff in the pull request:
https://github.com/apache/flink/pull/4274#discussion_r126871598
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/expressions/stringExpressions.scala
---
@@ -277,3 +278,47 @@ case class Overlay(
position.toRexNode)
}
}
+
+/**
+ * Returns the string that results from concatenating the arguments.
+ * Returns NULL if any argument is NULL.
+ */
+case class Concat(strings: Seq[Expression]) extends Expression with
InputTypeSpec {
+
+ override private[flink] def children: Seq[Expression] = strings
+
+ override private[flink] def resultType: TypeInformation[_] =
BasicTypeInfo.STRING_TYPE_INFO
+
+ override private[flink] def expectedTypes: Seq[TypeInformation[_]] =
STRING_TYPE_INFO :: Nil
+
+ override def toString: String = s"Concat($strings)"
+
+
+ override private[flink] def toRexNode(implicit relBuilder: RelBuilder):
RexNode = {
+ relBuilder.call(ScalarSqlFunctions.CONCAT, children.map(_.toRexNode))
+ }
+}
+
+/**
+ * Returns the string that results from concatenating the arguments and
separator.
+ * Returns NULL If the separator is NULL.
+ *
+ * Note: this user-defined function does not skip empty strings. However,
it does skip any NULL
+ * values after the separator argument.
+ **/
+case class ConcatWs(separator: Expression, strings: Seq[Expression])
+ extends Expression with InputTypeSpec {
+
+ override private[flink] def children: Seq[Expression] = Seq(separator)
++ strings
+
+ override private[flink] def resultType: TypeInformation[_] =
BasicTypeInfo.STRING_TYPE_INFO
+
+ override private[flink] def expectedTypes: Seq[TypeInformation[_]] =
STRING_TYPE_INFO :: Nil
+
+ override def toString: String = s"ConcatWs($separator, $strings)"
+
+
--- End diff --
remove empty line
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