精妙SQL語句-基礎(chǔ)-提升-技巧

1、精選優(yōu)質(zhì)文檔-傾情為你奉上一、基礎(chǔ)1、說明：創(chuàng)建數(shù)據(jù)庫Create DATABASE database-name2、說明：刪除數(shù)據(jù)庫drop database dbname3、說明：備份sql server- 創(chuàng)建 備份數(shù)據(jù)的 deviceUSE masterEXEC sp_addumpdevice 'disk', 'testBack', 'c:mssql7backupMyNwind_1.dat'- 開始 備份BACKUP DATABASE pubs TO testBack4、說明：創(chuàng)建新表create table tabname(col1 ty

2、pe1 not null primary key,col2 type2 not null,.)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、說明：刪除新表drop table tabname6、說明：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)類型也不能改變，唯一能改變的是增加varchar類型的

3、長度。7、說明：添加主鍵： Alter table tabname add primary key(col)說明：刪除主鍵： Alter table tabname drop primary key(col)8、說明：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、說明：創(chuàng)建視圖：create view viewname as select statement刪除視圖：drop view viewname10、說明：幾個(gè)簡單的基本的sql語句選擇：se

4、lect * from table1 where 范圍插入：insert into table1(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的語法很精妙，查資料!排序：select * from table1 order by field1,field2 desc總數(shù)：select count as total

5、count from table1求和：select sum(field1) as sumvalue 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

6、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自 TABLE1 就是來自 TABLE2。B： EXCEPT 運(yùn)算符EXCEPT 運(yùn)算符通過包括所有在 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

7、詞的幾個(gè)查詢結(jié)果行必須是一致的。12、說明：使用外連接A、left outer join：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、說明：復(fù)制表(只復(fù)制結(jié)構(gòu),源表名：a 新表名：b) (A

8、ccess可用)法一：select * into b from a where 1<>1法二：select top 0 * into b from a2、說明：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、說明：跨數(shù)據(jù)庫之間表的拷貝(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 where 條件例子：.from b in '"&Server.Map

9、Path(".")&"data.mdb" &"' where.4、說明：子查詢(表名1：a 表名2：b)select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3)5、說明：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 tabl

10、e.title=a.title) b6、說明：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.c7、說明：在線視圖查詢(表名1：a )select * from (Select a,b,c FROM a) T where t.a > 1;8、說明：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

11、 a,b,c, from table1 where a not between 數(shù)值1 and 數(shù)值29、說明：in 的使用方法select * from table1 where a not in (值1,值2,值4,值6)10、說明：兩張關(guān)聯(lián)表，刪除主表中已經(jīng)在副表中沒有的信息delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 )11、說明：四表聯(lián)查問題：select * from a left inner join b on a.a=b.b right i

12、nner join c on a.a=c.c inner join d on a.a=d.d where .12、說明：日程安排提前五分鐘提醒SQL: select * from 日程安排 where datediff('minute',f開始時(shí)間,getdate()>513、說明：一條sql 語句搞定數(shù)據(jù)庫分頁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、說明：前10條記錄

13、select top 10 * form table1 where 范圍15、說明：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(類似這樣的用法可以用于論壇每月排行榜,每月熱銷產(chǎn)品分析,按科目成績排名,等等.)select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b)16、說明：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 fr

14、om tableB) except (select a from tableC)17、說明：隨機(jī)取出10條數(shù)據(jù)select top 10 * from tablename order by newid()18、說明：隨機(jī)選擇記錄select newid()19、說明：刪除重復(fù)記錄Delete from tablename where id not in (select max(id) from tablename group by col1,col2,.)20、說明：列出數(shù)據(jù)庫里所有的表名select name from sysobjects where type='U'21、

15、說明：列出表里的所有的select name from syscolumns where id=object_id('TableName')22、說明：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，類似select 中的case。select type,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' t

16、hen 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 B 2光盤 A 2手機(jī) B 3手機(jī) C 323、說明：初始化表table1TRUNCATE TABLE table124、說明：選擇從10到15的記錄select top 5 * from (select top 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語句組合時(shí)用的較多“where 1=1” 是表示選擇全部 “w

17、here 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我們可以直接寫成set strSQL = 'select count(*) as Total from ' + tblNam

18、e + ' where 1=1 安定 '+ strWhere2、收縮數(shù)據(jù)庫-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dbcc shrinkdatabase(dbname)4、轉(zhuǎn)移數(shù)據(jù)庫給新用戶以已存在用戶權(quán)限exec sp_change_users_login 'update_one','newname','oldname'go5、檢查備份集RESTORE VERIFYONLY from disk='E:dvbbs

19、.bak'6、修復(fù)數(shù)據(jù)庫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)庫名Select LogicalFileName = 'tablename_

20、log', - 日志文件名MaxMinutes = 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),O

21、riginalSize) + ' 8K pages or ' +CONVERT(VARCHAR(30),(OriginalSize*8/1024) + 'MB'FROM sysfilesWhere name = LogicalFileNameCreate TABLE DummyTrans(DummyColumn char (8000) not null)DECLARE Counter INT,StartTime DATETIME,TruncLog VARCHAR(255)Select StartTime = GETDATE(),TruncLog = 'B

22、ACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY'DBCC SHRINKFILE (LogicalFileName, 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)AN

23、D (OriginalSize * 8 /1024) > NewSizeBEGIN - Outer loop.Select Counter = 0WHILE (Counter < OriginalSize / 16) AND (Counter < 50000)BEGIN - updateInsert DummyTrans VALUES ('Fill Log')Delete DummyTransSelect Counter = Counter + 1ENDEXEC (TruncLog)ENDSelect 'Final Size of ' + db

24、_name() + ' LOG is ' +CONVERT(VARCHAR(30),size) + ' 8K pages or ' +CONVERT(VARCHAR(30),(size*8/1024) + 'MB'FROM sysfilesWhere name = LogicalFileNameDrop TABLE DummyTransSET NOCOUNT OFF8、說明：更改某個(gè)表exec sp_changeobjectowner 'tablename','dbo'9、存儲(chǔ)更改全部表Create PROCEDU

25、RE dbo.User_ChangeObjectOwnerBatchOldOwner as NVARCHAR(128),NewOwner as NVARCHAR(128)ASDECLARE Name as NVARCHAR(128)DECLARE Owner as NVARCHAR(128)DECLARE OwnerName as NVARCHAR(128)DECLARE curObject CURSOR FORselect 'Name' = name,'Owner' = user_name(uid)from sysobjectswhere user_name(uid)=OldOwnerorder by nameOPEN curObjectFETCH NEXT FROM curObject INTO Name, OwnerWHILE(FETCH_STATUS=0)BEGINif Owner=OldOwnerbeginset OwnerName = OldOwner + '.' + rtrim(Name)exec sp_changeobjectowner OwnerName, New