數(shù)據(jù)庫(kù)基礎(chǔ)操作語(yǔ)句

1、一、基礎(chǔ)1、說(shuō)明：創(chuàng)建數(shù)據(jù)庫(kù)CREATE DATABASE database-name2、說(shuō)明：刪除數(shù)據(jù)庫(kù)drop database dbname3、說(shuō)明：備份sql server- 創(chuàng)建 備份數(shù)據(jù)的 deviceUSE masterEXEC sp_addumpdevice disk, testBack, c:mssql7backupMyNwind_1.dat- 開(kāi)始 備份BACKUP DATABASE pubs TO testBack4、說(shuō)明：創(chuàng)建新表create table tabname(col1 type1 not null primary key,col2 type2 not nul

2、l,.)根據(jù)已有的表創(chuàng)建新表：A：create table tab_new like tab_old (使用舊表創(chuàng)建新表)B：create table tab_new as select col1,col2 from tab_old definition only5、說(shuō)明：刪除新表drop table tabname6、說(shuō)明：增加一個(gè)列Alter table tabname add column col type注：列增加后將不能刪除。DB2中列加上后數(shù)據(jù)類(lèi)型也不能改變，唯一能改變的是增加varchar類(lèi)型的長(zhǎng)度。7、說(shuō)明：添加主鍵： Alter table tabname add prima

3、ry key(col)說(shuō)明：刪除主鍵： Alter table tabname drop primary key(col)8、說(shuō)明：創(chuàng)建索引：create unique index idxname on tabname(col.)刪除索引：drop index idxname注：索引是不可更改的，想更改必須刪除重新建。9、說(shuō)明：創(chuàng)建視圖：create view viewname as select statement刪除視圖：drop view viewname10、說(shuō)明：幾個(gè)簡(jiǎn)單的基本的sql語(yǔ)句選擇：select * from table1 where 范圍插入：insert into t

4、able1(field1,field2) values(value1,value2)刪除：delete from table1 where 范圍更新：update table1 set field1=value1 where 范圍查找：select * from table1 where field1 like %value1% -like的語(yǔ)法很精妙，查資料!排序：select * from table1 order by field1,field2 desc總數(shù)：select count as totalcount from table1求和：select sum(field1) as s

5、umvalue from table1平均：select avg(field1) as avgvalue from table1最大：select max(field1) as maxvalue from table1最?。簊elect min(field1) as minvalue from table111、說(shuō)明：幾個(gè)高級(jí)查詢運(yùn)算詞A： UNION 運(yùn)算符UNION 運(yùn)算符通過(guò)組合其他兩個(gè)結(jié)果表（例如 TABLE1 和 TABLE2）并消去表中任何重復(fù)行而派生出一個(gè)結(jié)果表。當(dāng) ALL 隨 UNION 一起使用時(shí)（即 UNION ALL），不消除重復(fù)行。兩種情況下，派生表的每一行不是來(lái)自 T

6、ABLE1 就是來(lái)自 TABLE2。B： EXCEPT 運(yùn)算符EXCEPT 運(yùn)算符通過(guò)包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重復(fù)行而派生出一個(gè)結(jié)果表。當(dāng) ALL 隨 EXCEPT 一起使用時(shí) (EXCEPT ALL)，不消除重復(fù)行。C： INTERSECT 運(yùn)算符INTERSECT 運(yùn)算符通過(guò)只包括 TABLE1 和 TABLE2 中都有的行并消除所有重復(fù)行而派生出一個(gè)結(jié)果表。當(dāng) ALL 隨 INTERSECT 一起使用時(shí) (INTERSECT ALL)，不消除重復(fù)行。注：使用運(yùn)算詞的幾個(gè)查詢結(jié)果行必須是一致的。12、說(shuō)明：使用外連接A、left outer joi

7、n：左外連接（左連接）：結(jié)果集幾包括連接表的匹配行，也包括左連接表的所有行。SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.cB：right outer join:右外連接(右連接)：結(jié)果集既包括連接表的匹配連接行，也包括右連接表的所有行。C：full outer join：全外連接：不僅包括符號(hào)連接表的匹配行，還包括兩個(gè)連接表中的所有記錄。二、提升1、說(shuō)明：復(fù)制表(只復(fù)制結(jié)構(gòu),源表名：a 新表名：b) (Access可用)法一：select * into b from a where 11法

8、二：select top 0 * into b from a2、說(shuō)明：拷貝表(拷貝數(shù)據(jù),源表名：a 目標(biāo)表名：b) (Access可用)insert into b(a, b, c) select d,e,f from b;3、說(shuō)明：跨數(shù)據(jù)庫(kù)之間表的拷貝(具體數(shù)據(jù)使用絕對(duì)路徑) (Access可用)insert into b(a, b, c) select d,e,f from b in 具體數(shù)據(jù)庫(kù) where 條件例子：.from b in &Server.MapPath(.&data.mdb & where.4、說(shuō)明：子查詢(表名1：a 表名2：b)select a,b,c from a w

9、here a IN (select d from b 或者: select a,b,c from a where a IN (1,2,3)5、說(shuō)明：顯示文章、提交人和最后回復(fù)時(shí)間select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b6、說(shuō)明：外連接查詢(表名1：a 表名2：b)select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c

10、7、說(shuō)明：在線視圖查詢(表名1：aselect * from (SELECT a,b,c FROM a) T where t.a 1;8、說(shuō)明：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 time2select a,b,c, from table1 where a not between 數(shù)值1 and 數(shù)值29、說(shuō)明：in 的使用方法select * from table1 where a not in (值1,值2,值4,值6)10、說(shuō)明：

11、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delete from table1 where not exists ( select * from table2 where table1.field1=table2.field111、說(shuō)明：四表聯(lián)查問(wèn)題：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 .12、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)

12、間,getdate()513、說(shuō)明：一條sql 語(yǔ)句搞定數(shù)據(jù)庫(kù)分頁(yè)select top 10 b.* from (select top 20 主鍵字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主鍵字段 = a.主鍵字段 order by a.排序字段14、說(shuō)明：前10條記錄select top 10 * form table1 where 范圍15、說(shuō)明：選擇在每一組b值相同的數(shù)據(jù)中對(duì)應(yīng)的a最大的記錄的所有信息(類(lèi)似這樣的用法可以用于論壇每月排行榜,每月熱銷(xiāo)產(chǎn)品分析,按科目成績(jī)排名,等等.)select a,b,c from tablen

13、ame ta where a=(select max(a) from tablename tb where tb.b=ta.b)16、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)17、說(shuō)明：隨機(jī)取出10條數(shù)據(jù)select top 10 * from tablename order by newid()18、說(shuō)明：隨機(jī)選擇記錄select newid()19、說(shuō)明：刪除重

14、復(fù)記錄Delete from tablename where id not in (select max(id) from tablename group by col1,col2,.)20、說(shuō)明：列出數(shù)據(jù)庫(kù)里所有的表名select name from sysobjects where type=U21、說(shuō)明：列出表里的所有的select name from syscolumns where id=object_id(TableName)22、說(shuō)明：列示type、vender、pcs字段，以type字段排列，case可以方便地實(shí)現(xiàn)多重選擇，類(lèi)似select 中的case。select type

15、,sum(case vender when A then pcs else 0 end),sum(case vender when C then pcs else 0 end),sum(case vender when B then pcs else 0 end) FROM tablename group by type顯示結(jié)果：type vender pcs電腦 A 1電腦 A 1光盤(pán) B 2光盤(pán) A 2手機(jī) B 3手機(jī) C 323、說(shuō)明：初始化表table1TRUNCATE TABLE table124、說(shuō)明：選擇從10到15的記錄select top 5 * from (select t

16、op 15 * from table order by id asc) table_別名 order by id desc三、技巧1、1=1，1=2的使用，在SQL語(yǔ)句組合時(shí)用的較多“where 1=1” 是表示選擇全部 “where 1=2”全部不選，如：if strWhere !=beginset strSQL = select count(*) as Total from + tblName + where + strWhereendelsebeginset strSQL = select count(*) as Total from + tblName + end我們可以直接寫(xiě)成set

17、 strSQL = select count(*) as Total from + tblName + where 1=1 安定 + strWhere2、收縮數(shù)據(jù)庫(kù)-重建索引DBCC REINDEXDBCC INDEXDEFRAG-收縮數(shù)據(jù)和日志DBCC SHRINKDBDBCC SHRINKFILE3、壓縮數(shù)據(jù)庫(kù)dbcc shrinkdatabase(dbname)4、轉(zhuǎn)移數(shù)據(jù)庫(kù)給新用戶以已存在用戶權(quán)限exec sp_change_users_login update_one,newname,oldnamego5、檢查備份集RESTORE VERIFYONLY from disk=E:dvb

18、bs.bak6、修復(fù)數(shù)據(jù)庫(kù)ALTER DATABASE dvbbs SET SINGLE_USERGODBCC CHECKDB(dvbbs,repair_allow_data_loss) WITH TABLOCKGOALTER DATABASE dvbbs SET MULTI_USERGO7、日志清除SET NOCOUNT ONDECLARE LogicalFileName sysname,MaxMinutes INT,NewSize INTUSE tablename - 要操作的數(shù)據(jù)庫(kù)名SELECT LogicalFileName = tablename_log, - 日志文件名MaxMin

19、utes = 10, - Limit on time allowed to wrap log.NewSize = 1 - 你想設(shè)定的日志文件的大小(M)- Setup / initializeDECLARE OriginalSize intSELECT OriginalSize = sizeFROM sysfilesWHERE name = LogicalFileNameSELECT Original Size of + db_name() + LOG is +CONVERT(VARCHAR(30),OriginalSize) + 8K pages or +CONVERT(VARCHAR(30

20、),(OriginalSize*8/1024) + MBFROM sysfilesWHERE name = LogicalFileNameCREATE TABLE DummyTrans(DummyColumn char (8000) not null)DECLARE Counter INT,StartTime DATETIME,TruncLog VARCHAR(255)SELECT StartTime = GETDATE(),TruncLog = BACKUP LOG + db_name() + WITH TRUNCATE_ONLYDBCC SHRINKFILE (LogicalFileNam

21、e, NewSize)EXEC (TruncLog)- Wrap the log if necessary.WHILE MaxMinutes DATEDIFF (mi, StartTime, GETDATE() - time has not expiredAND OriginalSize = (SELECT size FROM sysfiles WHERE name = LogicalFileName)AND (OriginalSize * 8 /1024) NewSizeBEGIN - Outer loop.SELECT Counter = 0WHILE (Counter OriginalS

22、ize / 16) AND (Counter 50000)BEGIN - updateINSERT DummyTrans VALUES (Fill Log)DELETE DummyTransSELECT Counter = Counter + 1ENDEXEC (TruncLog)ENDSELECT Final Size of + db_name() + LOG is +CONVERT(VARCHAR(30),size) + 8K pages or +CONVERT(VARCHAR(30),(size*8/1024) + MBFROM sysfilesWHERE name = LogicalFileNameDROP TABLE DummyTransSET NOCOUNT OFF8、說(shuō)明：更改某個(gè)表exec sp_changeobjectowner tablename