SQL Server：从文本列中提取主题标签

Question

我在这里理解这个答案： 如何从T-SQL中的字符串中提取标签，解释了如何从声明的字符串变量中提取标签，但是我如何将此操作应用于整个字符串列？

Answer 1

使用交叉申请。 只是为了好玩 ，请删除最后的WHERE，然后看看会发生什么

例

Declare @YourTable table (ID int,SomeText varchar(max))
Insert into @YourTable values
 (1, '#want to extract all #hastag out of this string, #delhi #Traffic')
,(2, '#bunny #hastag #donetodeath')

Select A.ID
      ,B.*
 From  @YourTable A
 Cross Apply (
                Select RetSeq = Row_Number() over (Order By (Select null))
                      ,RetVal = LTrim(RTrim(B.i.value('(./text())[1]', 'varchar(max)')))
                From  (Select x = Cast('<x>' + replace((Select replace(replace(A.SomeText,char(13),' '),' ','§§Split§§') as [*] For XML Path('')),'§§Split§§','</x><x>')+'</x>' as xml).query('.')) as A 
                Cross Apply x.nodes('x') AS B(i)
             ) B
 Where B.RetVal like '#%'

退货

ID  RetSeq  RetVal
1   1       #want
1   5       #hastag
1   10      #delhi
1   11      #Traffic
2   1       #bunny
2   2       #hastag
2   3       #donetodeath