select distinct aa as 姓名,bc as 语文,cc as 数学 from 表1 a inner join (select a,c from 表1 where b='语文') b on aa=ba i

就是backlight。backlight noun [mass noun]illumination from behind 背后照明verb past -lit; past participle -lit 或 lighte

List&ltWebElent&gt找 optionselector 。selectByIndex  selectByValue  SelectByTextfrom selenium.webdriver.common.k

access ： 表.select 字段a &amp表.字段B as 字段x from 表；Oracle： 表.select 字段a || 表.字段B 字段x from 表；Select * From (Select 字段1 As

1.MS SQL Server，随机查询20条select top 20  * from  表名order by newid()2.My SQL:，随机查询20条select  *  from  表名 order by rand() l

update t_time t1set t1.Bks=(select max(t2.EndTime) from t_diaoyonglian0703 t2 where t1.TraceID=t2.TraceID and t2.Site=&#

select hour(create_time) AS saleHour, count(id) AS saleCount from tableName where date_format(create_time, ‘%Y-%m-%d’

统计所有记录的数量：SELECT COUNT(*) FROM table_name统计某列的数量：SELECT COUNT(column_name) FROM table_namewhere 条件查询表数据： select *from 表

select case team when 1 then '甲' when 2 then ' 乙' when 3 then '丙' when 4 then ‘丁'end

select case team when 1 then '甲' when 2 then ' 乙' when 3 then '丙' when 4 then ‘丁'end

虚拟列就是人为增加的列：set @rn=0select (@rn:=@rn+1) rn,name from (select id,name from tasks order by id)name第一种方法：select (@i:=@i+

update pre_forum_typeoptionvar set value = (select subject form pre_forum_thread where pre_forum_thread.tid = (select ti

4张表依次使用unionSELECTE.NAME ,E.COLUMN1,E.COLUMN2,E.COLUMN3,E.COLUMN4 FROM (SELCT NAME FROM A UNIONSELCT NAME FROM BUNIONS

mysql用limit，没有oracle那么麻烦。从index 0 开始，取5条记录select * from table limit 0,5还可以取中间的记录：从index 5开始，连续取10条记录select * from table

mysql中有group_concat()()可以合并多行内容select AID,ANAME,(select group_concat(VALUE) from B where B.AID=A.AID) as AVALUE from A(1

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SELECT name,mun,COUNT(1) cnt FROM table_baiduGROUP BY name,mun HAVING name IN('Y100','X100')SELECT t

SELECT @rownum:=@rownum+1 AS rownum, tablename.*FROM (SELECT @rownum:=0) r, tablenameSELECTcity_name, title, COUNT(*

select disntinct r.NOTIFY_ID from officialdoc_readers as r where r.user_id = 'xiaoma' 加个disntinct 试试