1.查询当前菜单节点对应的子菜单节点的数据
SELECT
*
FROM
AUTH_MENU_INF
START WITH MENU_ID='26'
CONNECT BY PRIOR MENU_ID = MENU_PAR_ID
2
updatexlemailt sett.mobile=(selects.mobilefromz_zs wheret.name=s.name )
whereexists(select1 fromz_zs wheret.name=s.name ) ;
需要使用where条件限制更新的记录，否则不匹配的被更为空
3
Update a set a.ori_price=a.price,a.price=a.ori_priceWhere a.id=1 ;
Update a a1, a a2
set a1.ori_price=a2.price,a1.price=a2.ori_price
Where a1.id=a2.id and a1.id=1 ;
MySQL中前一种写法因更新的先后顺序问题导致price字段并未更新（oracle/sqlserver是等其他数据库不存在此问题）
4
可按照如下的随机顺序检索数据行，如下：
mysql> SELECT * FROM tbl_name ORDER BY RAND();
5.
select count(*),DATE_FORMAT(createTime,'%Y%m%d') days from A sc
WHERE
sc.createTime BETWEEN '2017-07-01'
AND '2017-07-31'
group by days