[ 
https://issues.apache.org/jira/browse/FLINK-6925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16062646#comment-16062646
 ] 

ASF GitHub Bot commented on FLINK-6925:
---------------------------------------

Github user twalthr commented on a diff in the pull request:

    https://github.com/apache/flink/pull/4138#discussion_r123946426
  
    --- 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
    --- End diff --
    
    This is a internal method. We don't need varargs here, we can use 
`Array[String]`.


> 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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