精妙的"SQL"语句:
◆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') &brvbar;&brvbar; '/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