數(shù)據(jù)庫(kù)語(yǔ)法從基礎(chǔ)到精通

第 4 頁(yè) 精妙Sql語(yǔ)句

精妙Sql語(yǔ)句
1． 判斷a表中有而b表中沒(méi)有的記錄

select a.* from tbl1 a

left join tbl2 b

on a.key = b.key

where b.key is null

雖然使用in也可以實(shí)現(xiàn)，但是這種方法的效率更高一些

2． 新建一個(gè)與某個(gè)表相同結(jié)構(gòu)的表

select * into b

from a where 1<>1

3．between的用法,between限制查詢數(shù)據(jù)范圍時(shí)包括了邊界值,not between不包括

select * from table1 where time between time1 and time2

select a,b,c, from table1 where a not between 數(shù)值1 and 數(shù)值2

4. 說(shuō)明：包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重復(fù)行而派生出一個(gè)結(jié)果表

(select a from tableA ) except (select a from tableB) except (select a from tableC)

5. 初始化表，可以將自增長(zhǎng)表的字增長(zhǎng)字段置為1

TRUNCATE TABLE table1

6．多語(yǔ)言設(shè)置數(shù)據(jù)庫(kù)或者表或者order by的排序規(guī)則

--修改用戶數(shù)據(jù)庫(kù)的排序規(guī)則

ater database dbname collate SQL_Latin1_General_CP1_CI_AS

--修改字段的排序規(guī)則

alter table a alter column c2 varchar(50) collate SQL_Latin1_General_CP1_CI_AS

--按姓氏筆畫(huà)排序

select * from 表名 order by 列名 Collate Chinese_PRC_Stroke_ci_as

--按拼音首字母排序

select * from 表名 order by 列名 Collate Chinese_PRC_CS_AS_KS_WS

7．列出所有的用戶數(shù)據(jù)表：

SELECT TOP 100 PERCENT o.name AS 表名

FROM dbo.syscolumns c INNER JOIN

dbo.sysobjects o ON o.id = c.id AND objectproperty(o.id, N'IsUserTable') = 1 AND

o.name <> 'dtproperties' LEFT OUTER JOIN

dbo.sysproperties m ON m.id = o.id AND m.smallid = c.colorder

WHERE (c.colid = 1)

ORDER BY o.name, c.colid

 

8．列出所有的用戶數(shù)據(jù)表及其字段信息：

SELECT TOP 100 PERCENT c.colid AS 序號(hào), o.name AS 表名, c.name AS 列名,

t.name AS 類型, c.length AS 長(zhǎng)度, c.isnullable AS 允許空,

CAST(m.[value] AS Varchar(100)) AS 說(shuō)明

FROM dbo.syscolumns c INNER JOIN

dbo.sysobjects o ON o.id = c.id AND objectproperty(o.id, N'IsUserTable') = 1 AND

o.name <> 'dtproperties' INNER JOIN

dbo.systypes t ON t.xusertype = c.xusertype LEFT OUTER JOIN

dbo.sysproperties m ON m.id = o.id AND m.smallid = c.colorder

ORDER BY o.name, c.colid

9．Left，right Join的另外一種簡(jiǎn)潔的寫(xiě)法

select * from a,b where a.id *= b.id --（*= 相當(dāng)于 LEFT JOIN）

select * from a,b where a.id =* b.id --（=* 相當(dāng)于 Right JOIN）

10．Update from 和 delete from

11．得到表中最小的未使用的ID號(hào)

SELECT (CASE WHEN EXISTS(SELECT * FROM Handle b WHERE b.HandleID = 1)

THEN MIN(HandleID) + 1 ELSE 1 END) as HandleID

FROM Handle

WHERE NOT HandleID IN (SELECT a.HandleID - 1 FROM Handle a)

12．隨機(jī)取得記錄

SELECT TOP 10 * FROM T1 ORDER BY NEWID()

精妙SQL語(yǔ)句介紹

　　如何從一位菜鳥(niǎo)蛻變成為高手，靈活使用的SQL語(yǔ)句是必不可少的。本文收集了部分比較經(jīng)典，常用的SQL語(yǔ)句供大家參考，希望對(duì)大家有所幫助。

　　說(shuō)明：復(fù)制表(只復(fù)制結(jié)構(gòu),源表名：a 新表名：b)　　

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

　　說(shuō)明：拷貝表(拷貝數(shù)據(jù),源表名：a 目標(biāo)表名：b)　　

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

　　說(shuō)明：顯示文章、提交人和最后回復(fù)時(shí)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(shuō)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

　　說(shuō)明：日程安排提前五分鐘提醒　　

　　SQL: select * from 日程安排 where datediff('minute',f開(kāi)始時(shí)間,getdate())>5　　

　　說(shuō)明：兩張關(guān)聯(lián)表，刪除主表中已經(jīng)在副表中沒(méi)有的信息

　　SQL: 　　

　　delete from info where not exists ( select * from infobz where info.infid=infobz.infid

　　說(shuō)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(shuō)明：--

　　SQL: 　　

　　select * from studentinfo where not exists(select * from student where studentinfo.id=student.id) and 系名稱='"&strdepartmentname&"' and 專業(yè)名稱='"&strprofessionname&"' order by 性別,生源地,高考總成績(jī)

　　說(shuō)明：

　　從數(shù)據(jù)庫(kù)中去一年的各單位電話費(fèi)統(tǒng)計(jì)(電話費(fèi)定額賀電化肥清單兩個(gè)表來(lái)源）

　　SQL: 　

　　SELECT a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, 'yyyy') AS telyear,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '01', a.factration)) AS JAN,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '02', a.factration)) AS FRI,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '03', a.factration)) AS MAR,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '04', a.factration)) AS APR,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '05', a.factration)) AS MAY,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '06', a.factration)) AS JUE,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '07', a.factration)) AS JUL,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '08', a.factration)) AS AGU,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '09', a.factration)) AS SEP,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '10', a.factration)) AS OCT,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '11', a.factration)) AS NOV,

　　 SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '12', a.factration)) AS DEC

　　FROM (SELECT a.userper, a.tel, a.standfee, b.telfeedate, b.factration

　　 FROM TELFEESTAND a, TELFEE b

　　 WHERE a.tel = b.telfax) a

　　GROUP BY a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, 'yyyy')

　　說(shuō)明：四表聯(lián)查問(wèn)題：　　

　　SQL: select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where .....

　　說(shuō)明：得到表中最小的未使用的ID號(hào)

　　SQL:　

　　SELECT (CASE WHEN EXISTS(SELECT * FROM Handle b WHERE b.HandleID = 1) THEN MIN(HandleID) + 1 ELSE 1 END) as HandleID

　　 FROM Handle

　　 WHERE NOT HandleID IN (SELECT a.HandleID - 1 FROM Handle a)