sql技巧(备忘)

◆复制表(只复制结构,源表名：a 新表名：b)

 

SQL: select * into b from a where 1<>1

 

◆拷贝表(拷贝数据,源表名：a 目标表名：b)

 

SQL: insert into b(a, b, c) select d,e,f from b; 　

 

◆显示文章、提交人和最后回复时间

 

SQL: select a.title,a.username,b.adddate from table a,

(select max(adddate) adddate from table where table.title=a.title) b 　

 

◆说明：外连接查询(表名1：a 表名2：b)

 

SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a =

b.c

 

◆日程安排提前五分钟提醒

 

SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 　　

 

◆两张关联表，删除主表中已经在副表中没有的信息

 

SQL:

delete from info where not exists

( select * from infobz where info.infid=infobz.infid )

 

◆说明：

 

SQL:

SELECT A.NUM, A.NAME, B.UPD_DATE, B.PREV_UPD_DATE

FROM TABLE1,(SELECT X.NUM, X.UPD_DATE, Y.UPD_DATE

PREV_UPD_DATE FROM (SELECT NUM, UPD_DATE, INBOUND_QTY,

STOCK_ONHAND FROM TABLE2 WHERE TO_CHAR(UPD_DATE,

'YYYY/MM') = TO_CHAR(SYSDATE, 'YYYY/MM')) X,

(SELECT NUM, UPD_DATE, STOCK_ONHAND FROM TABLE2

WHERE TO_CHAR(UPD_DATE,'YYYY/MM') = TO_CHAR(TO_DATE

(TO_CHAR(SYSDATE, 'YYYY/MM') ¦¦ '/01','

YYYY/MM/DD') - 1, 'YYYY/MM') ) Y, WHERE X.NUM = Y.NUM

（+）AND X.INBOUND_QTY + NVL(Y.STOCK_ONHAND,0) <>

X.STOCK_ONHAND ) B WHERE A.NUM = B.NUM

 

◆说明：

 

SQL:

select * from studentinfo where not exists(select * from student where

studentinfo.id=student.id) and 系名称='"&strdepartmentname&"' and 专业名称

='"&strprofessionname&"' order by 性别,生源地,高考总成绩。