sql-server - 在 SQL 中拆分和连接值

Question

我有如下两个不同的表，并且对 sql 查询有特定要求。

Table1:
Name   RuleNumber
Tom    1,2
Pete   1,3

Table2:
RuleNumber  Description
1           Rule1
2           Rule2
3           Rule3

如何获得类似下面的 sql 查询结果

Name    Description
Tom     Rule1, Rule2
Pete    Rule1, Rule3

Answer 1

您首先需要一个自定义拆分函数来分隔分隔列表，然后使用它FOR XML PATH来组合描述。这是您的最终查询

select  t1.Name,
        STUFF(( SELECT ',' + Description
                FROM    table2 AS t2 
                WHERE   t2.ruleNumber in (select s from dbo.fn_split(t1.RuleNumber, ','))
        ORDER BY ruleNumber
        FOR XML PATH('')), 1, 1, '') as 'Description'
from    table1 t1

这是拆分功能的代码。

create function [dbo].[fn_Split]
(
    @String     varchar(8000) ,
    @Delimiter  varchar(10)
)
returns @tbl table (s varchar(1000))
as

begin
declare @i int ,
    @j int
    select  @i = 1
    while @i <= len(@String)
    begin
        select  @j = charindex(@Delimiter, @String, @i)
        if @j = 0
        begin
            select  @j = len(@String) + 1
        end
        insert  @tbl select substring(@String, @i, @j - @i)
        select  @i = @j + len(@Delimiter)
    end
    return
end

Answer 2

Table1 的 RuleNumber 如何有多个值？它是一个字符串吗？我会假设它是：

Name / RuleNumber
Tom  / 1
Tom  / 2

然后，查询将是：

select
  Name,
  ( 
     select Description 
     from Table2 as t2 
     where t1.ruleNumber = t2.ruleNumber
  ) as Description
from 
  table1 as t1