精妙的SQL語句技巧集合

精妙的"SQL"語句:

◆複製表(只複製結構,源表名：a 新表名：b)

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

◆拷貝表(拷貝資料,源表名：a 目標表名：b)

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

◆顯示文章、提交人和最後回復時間

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

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

◆說明：外連接查詢(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

◆排程提前五分鐘提醒

SQL: select * from 排程 where datediff('minute',f開始時間,getdate())>5

◆兩張關聯表，刪除主表中已經在副表中沒有的資訊

SQL:

delete from info where not exists

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

◆說明：

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

◆說明：

SQL:

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

studentinfo.id=student.id) and 系名稱='"&strdepartmentname&"' and 專業名稱

='"&strprofessionname&"' order by 性別,生源地,高考總成績。