将 sql 结果作为单个字符串返回答案

【问题标题】：Return sql results as a single string将 sql 结果作为单个字符串返回
【发布时间】：2013-12-29 04:25:48
【问题描述】：

我有以下查询返回超过 1 个结果（最多大约 10 行而不是更多！），我怎样才能将所有结果作为单个字符串返回？

SELECT DISTINCT(e.Username)
FROM TblLeaveEmployee l
JOIN TblLeaveApprovalsBy a on l.EmployeeId = a.UserID
JOIN TblEmployee e on l.EmployeeId = e.id
where l.EmployeeId IN 
  (select UserID 
   FROM TblLeaveApprovalsBy 
   WHERE ApprovalUserID IN
     (SELECT ApprovalUserID from TblLeaveApprovalsBy where UserID = 77))

已尝试如下使用STUFF，但无法正常工作：

DECLARE @CodeNameString varchar(100)
SELECT 
   @CodeNameString = STUFF(
SELECT DISTINCT(e.Username)
FROM TblLeaveEmployee l
JOIN TblLeaveApprovalsBy a on l.EmployeeId = a.UserID
JOIN TblEmployee e on l.EmployeeId = e.id
where l.EmployeeId IN 
  (select UserID 
   FROM TblLeaveApprovalsBy
   WHERE ApprovalUserID IN
     (SELECT ApprovalUserID from TblLeaveApprovalsBy where UserID = 77)))

【问题讨论】：

试试这个http://stackoverflow.com/questions/17990986/concatenate-rows-for-one-column-sql

标签： database sql-server-2008 select-query

【解决方案1】：

如果你有大量的行，这将是一个问题。

试试这个

DECLARE t CURSOR FOR  
select Col1 from [Table] where crite1 = ???

open t

declare @v varchar(255)
declare @Res varchar(max)
 set @Res = ''
 set @v = ''
FETCH NEXT FROM t into @v
while (@@FETCH_STATUS = 0) begin
    set @Res = @Res + @v + '|'
    FETCH NEXT FROM t into @v
end
print @Res

close t
deallocate t

【讨论】：

返回的最大行数注意超过 10
那么一切顺利，只需将这个查询 [select Col1 from [Table] where crite1 = ???] 替换为您的查询

【解决方案2】：

   DECLARE @CodeNameString VARCHAR(MAX)=NULL
   SELECT @CodeNameString = COALESCE(@CodeNameString+',' ,'') + Username 
   FROM
   (
   SELECT DISTINCT(e.Username) Username
   FROM TblLeaveEmployee l
   JOIN TblLeaveApprovalsBy a on l.EmployeeId = a.UserID
   JOIN TblEmployee e on l.EmployeeId = e.id
   where   l.EmployeeId IN (select UserID FROM TblLeaveApprovalsBy
              WHERE ApprovalUserID IN(SELECT ApprovalUserID from TblLeaveApprovalsBy    where UserID = 77))) x
   SELECT @CodeNameString

【讨论】：

Msg 156, Level 15, State 1, Line 11 关键字“SELECT”附近的语法不正确。
这在您的查询中，我只是将其包装起来并添加了前三行和最后一行。尝试运行内部查询，看看是否可以在那里找到问题
好的，我明白了问题所在；刚刚对其进行了编辑（将 x 为内部查询添加别名）

【解决方案3】：

DECLARE t CURSOR FOR  
SELECT DISTINCT(e.Username)
FROM TblLeaveEmployee l
JOIN TblLeaveApprovalsBy a on l.EmployeeId = a.UserID
JOIN TblEmployee e on l.EmployeeId = e.id
where l.EmployeeId IN 
(select UserID 
   FROM TblLeaveApprovalsBy 
   WHERE ApprovalUserID IN
     (SELECT ApprovalUserID from TblLeaveApprovalsBy where UserID = 77))

open t

declare @v varchar(255)
declare @Res varchar(max)
 set @Res = ''
 set @v = ''
FETCH NEXT FROM t into @v
while (@@FETCH_STATUS = 0) begin
    set @Res = @Res + @v + '|'
    FETCH NEXT FROM t into @v
end
print @Res

close t
deallocate t

【讨论】：