What is the meaning of SELECT … FOR XML PATH(' '),1,1)?

前端 未结 2 1116
遥遥无期
遥遥无期 2020-12-02 10:43

I am learning sql in one of the question and here I saw usage of this,can some body make me understand what xml path(\'\') mean in sql? and yes,i browsed through web pages I

2条回答
  •  庸人自扰
    2020-12-02 11:20

    There's no real technique to learn here. It's just a cute trick to concatenate multiple rows of data into a single string. It's more a quirky use of a feature than an intended use of the XML formatting feature.

    SELECT ',' + ColumnName ... FOR XML PATH('')
    

    generates a set of comma separated values, based on combining multiple rows of data from the ColumnName column. It will produce a value like ,abc,def,ghi,jkl.

    STUFF(...,1,1,'')
    

    Is then used to remove the leading comma that the previous trick generated, see STUFF for details about its parameters.

    (Strangely, a lot of people tend to refer to this method of generating a comma separated set of values as "the STUFF method" despite the STUFF only being responsible for a final bit of trimming)

提交回复
热议问题