--方法1
DECLARE @STR VARCHAR(8000)
SELECT @STR=ISNULL(@STR+",","")+userID FROM (SELECT DISTINCT userID FROM Users)AS T
SELECT @STR AS NAME
结果：
--方法2
decl
将sql的多行查询结果拼接成一个字符串
DECLARE @S VARCHAR(MAX)=
(
SELECT STUFF( (select distinct ","+CAST(C1 AS VARCHAR(20))
FROM (
SELECT 1 AS C1,2 AS C2
UNION ALL SELECT
