SQL 常用函数使用

Distinct 去重复。性能上和 GROUP BY 差异据说有点点优势，GROUP BY 存在毕竟不是用来去重的，GROUP BY 用作分组，当然可以做去重动作

select DISTINCT [列1]，[列2]... from [数据库].[dbo].[表名]

 

CHARINDEX

charindex 取指定字符在字符串中的位置

SELECT CHARINDEX("ab","123456abcde");



// 结合表
SELECT CHARINDEX("ab",[列名]) as [abIndex],[列名] from [数据库].[dbo].[数据表] ;

 

SUBSTRING

Substring 截取字符

 

SELECT DISTINCT   LTRIM(RTRIM(LOWER(SUBSTRING([列 0],0,CHARINDEX(":$",[列 0]))))) as [email], [列 0] as [txt]
  FROM [Ve_Old].[dbo].[bf_1]