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https://issues.apache.org/jira/browse/FLINK-6925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16063076#comment-16063076
]
ASF GitHub Bot commented on FLINK-6925:
---------------------------------------
Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/4138#discussion_r124007599
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/functions/ScalarFunctions.scala
---
@@ -0,0 +1,79 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.flink.table.runtime.functions
+
+import scala.annotation.varargs
+import java.math.{BigDecimal => JBigDecimal}
+import java.lang.{StringBuffer => JStringBuffer}
+
+/**
+ * All build-in scalar scalar functions.
+ */
+class ScalarFunctions {}
+
+object ScalarFunctions {
+
+ def power(a: Double, b: JBigDecimal): Double = {
+ Math.pow(a, b.doubleValue())
+ }
+
+ /**
+ * Returns the string that results from concatenating the arguments.
+ * Returns NULL if any argument is NULL.
+ */
+ @varargs
+ def concat(args: String*): String = {
+ val sb = new JStringBuffer
+ var i = 0
+ while (i < args.length) {
+ if (args(i) == null) {
+ return null
+ }
+ sb.append(args(i))
+ i += 1
+ }
+ sb.toString
+ }
+
+ /**
+ * Returns the string that results from concatenating the arguments and
separator.
+ * Returns NULL If the separator is NULL.
+ *
+ * Note: CONCAT_WS() does not skip empty strings. However, it does skip
any NULL values after
+ * the separator argument.
+ *
+ * @param args The first element of argument is the separator for the
rest of the arguments.
+ */
+ @varargs
+ def concat_ws(args: String*): String = {
+ val separator = args(0)
+ if (null == separator) {
+ return null
+ }
+
+ val sb = new JStringBuffer
+
+ var i = 1
+ val dataList = args.filter(null != _)
--- End diff --
Yes, good catch. :)
> Add CONCAT/CONCAT_WS supported in SQL
> -------------------------------------
>
> Key: FLINK-6925
> URL: https://issues.apache.org/jira/browse/FLINK-6925
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Affects Versions: 1.4.0
> Reporter: sunjincheng
> Assignee: sunjincheng
>
> CONCAT(str1,str2,...)Returns the string that results from concatenating the
> arguments. May have one or more arguments. If all arguments are nonbinary
> strings, the result is a nonbinary string. If the arguments include any
> binary strings, the result is a binary string. A numeric argument is
> converted to its equivalent nonbinary string form.
> CONCAT() returns NULL if any argument is NULL.
> * Syntax:
> CONCAT(str1,str2,...)
> * Arguments
> ** str1,str2,... -
> * Return Types
> string
> * Example:
> CONCAT('F', 'lin', 'k') -> 'Flink'
> CONCAT('M', NULL, 'L') -> NULL
> CONCAT(14.3) -> '14.3'
> * See more:
> ** [MySQL|
> https://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_concat]
> CONCAT_WS() stands for Concatenate With Separator and is a special form of
> CONCAT(). The first argument is the separator for the rest of the arguments.
> The separator is added between the strings to be concatenated. The separator
> can be a string, as can the rest of the arguments. If the separator is NULL,
> the result is NULL.
> * Syntax:
> CONCAT_WS(separator,str1,str2,...)
> * Arguments
> ** separator -
> ** str1,str2,... -
> * Return Types
> string
> * Example:
> CONCAT_WS(',','First name','Second name','Last Name') -> 'First name,Second
> name,Last Name'
> * See more:
> ** [MySQL|
> https://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_concat-ws]
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