将规范化为管道分隔列表

Question

  

可能重复：
  Is there a way to create a SQL Server function to “join” multiple rows from a subquery into a single delimited field?

我有这样的标签：

cust   acc
-----------
a      1
b      2
b      3
c      4
c      5
c      6

我想将上面的反规范化为以下形式

cust    acc
---------------
a       1
b       2|3
c       4|5|6

请注意，acc列现在应包含任何客户的管道分隔的帐户列表。此外，客户可能的帐户数量也可以变化。

如何使用SQL执行此操作？

Answer 1

试试这个：

SELECT cust, acc = 
    STUFF((SELECT '| ' +CAST( acc as varchar(20))
           FROM <table> b 
           WHERE b.cust = a.cust 
          FOR XML PATH('')), 1, 2, '')
FROM <table> a
GROUP BY cust

SQL Fiddle Demo

Answer 2

如果你想通过Cust（在MySQL中像Group_Concate这样的东西）进行分组，那么在SQL Server中没有任何方法。 所以试试这个：

SELECT * FROM (
        SELECT  DISTINCT cust
        FROM    t
        ) table2
    CROSS APPLY
        (SELECT  CASE ROW_NUMBER() 
          OVER(ORDER BY acc) 
          WHEN 1 THEN '' ELSE ' | ' END + 
          (cast(acc as varchar))
        FROM    t table3
        WHERE   table3.cust = table2.cust
        ORDER BY acc
        FOR XML PATH ('')
        ) table3(acc)

See this SQLFiddle

另见：Group columns into multiple rows and Group_concate like MySQL in SQL Server

Answer 3

试试这个：

 select cust,
STUFF((select '|'+cast(acc as varchar) from c1 where c1.cust = c2.cust for XML   path('')),1,1,'') as acc from c1 c2
group by cust