select (@rowNO := @rowNo+) AS rowno,ip,startcount  from (SELECT ip,startcount  FROM client where appname='' ) a,(select @rowNO :=) b 

select id,appname,max(version) as version,updatetime from updater where = group by appname limit ,;

string sql = string.Format("select id,appname,max(version) as version,updatetime from updater where 1=1 {0} group by appname limit {1},{2};",gridProp.FilterString,(gridProp.SelectPage-)* gridProp.PageSize,gridProp.PageSize);

查询

今天

select * from 表名 where to_days(时间字段名) = to_days(now());

昨天

SELECT * FROM 表名 WHERE TO_DAYS( NOW( ) ) - TO_DAYS( 时间字段名) <= 1

7天

SELECT * FROM 表名 where DATE_SUB(CURDATE(), INTERVAL 7 DAY) <= date(时间字段名)

近30天

SELECT * FROM 表名 where DATE_SUB(CURDATE(), INTERVAL 30 DAY) <= date(时间字段名)

本月

SELECT * FROM 表名 WHERE DATE_FORMAT( 时间字段名, '%Y%m' ) = DATE_FORMAT( CURDATE( ) , '%Y%m' )

上一月

SELECT * FROM 表名 WHERE PERIOD_DIFF( date_format( now( ) , '%Y%m' ) , date_format( 时间字段名, '%Y%m' ) ) =1

4, 将表B中的字段插入到表A中。

INSERT INTO A (id) SELECT id FROM B