轉(zhuǎn)自http://www.cnblogs.com/0351jiazhuang/p/4530366.html

SQL是(Structured Query Language)結(jié)構(gòu)化查詢語言的簡稱，下面趙一鳴隨筆博客從基礎(chǔ)知識擦囊、判斷對象和應(yīng)用技巧等方面音同，介紹了SQL的應(yīng)用方法迄委。

基礎(chǔ)

創(chuàng)建數(shù)據(jù)庫

創(chuàng)建之前判斷該數(shù)據(jù)庫是否存在

if exists (select * from sysdatabases where name='databaseName')

drop database databaseName

go

Create DATABASE database-name

刪除數(shù)據(jù)庫

drop database dbname

備份sql server

— 創(chuàng)建 備份數(shù)據(jù)的 device

USE master

EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat'

— 開始 備份

BACKUP DATABASE pubs TO testBack

創(chuàng)建新表

create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)

根據(jù)已有的表創(chuàng)建新表：

A：go

use 原數(shù)據(jù)庫名

go

select * into 目的數(shù)據(jù)庫名.dbo.目的表名 from 原表名(使用舊表創(chuàng)建新表)

B：create table tab_new as select col1,col2… from tab_old definition only

創(chuàng)建序列

create sequence SIMON_SEQUENCE

minvalue 1 — 最小值

maxvalue 999999999999999999999999999 最大值

start with 1 開始值

increment by 1 每次加幾

cache 20;

刪除新表

drop table tabname

增加一個列

Alter table tabname add column col type

注：列增加后將不能刪除厅克。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類型的長度譬嚣。

添加主鍵

Alter table tabname add primary key(col)

說明：刪除主鍵： Alter table tabname drop primary key(col)

創(chuàng)建索引

create [unique] index idxname on tabname(col….)

刪除索引：drop index idxname on tabname

注：索引是不可更改的懈贺，想更改必須刪除重新建。

創(chuàng)建視圖

create view viewname as select statement

刪除視圖：drop view viewname

幾個簡單的基本的sql語句

選擇：select * 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%’ （所有包含‘value1’這個模式的字符串）—like的語法很精妙拣展，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 sumvalue from table1

平均：select avg(field1) as avgvalue from table1

最大：select max(field1) as maxvalue from table1

最信碚印：select min(field1) as minvalue from table1[separator]

幾個高級查詢運算詞

A： UNION 運算符

UNION 運算符通過組合其他兩個結(jié)果表（例如 TABLE1 和 TABLE2）并消去表中任何重復(fù)行而派生出一個結(jié)果表。當(dāng) ALL 隨 UNION 一起使用時（即 UNION ALL）备埃，不消除重復(fù)行姓惑。兩種情況下，派生表的每一行不是來自 TABLE1 就是來自 TABLE2按脚。

B： EXCEPT 運算符

EXCEPT 運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)行而派生出一個結(jié)果表于毙。當(dāng) ALL 隨 EXCEPT 一起使用時 (EXCEPT ALL)，不消除重復(fù)行辅搬。

C： INTERSECT 運算符

INTERSECT 運算符通過只包括 TABLE1 和 TABLE2 中都有的行并消除所有重復(fù)行而派生出一個結(jié)果表唯沮。當(dāng) ALL 隨 INTERSECT 一起使用時 (INTERSECT ALL)，不消除重復(fù)行堪遂。

注：使用運算詞的幾個查詢結(jié)果行必須是一致的介蛉。

使用外連接

A、left outer join：

左外連接（左連接）：結(jié)果集既包括連接表的匹配行溶褪，也包括左連接表的所有行甘耿。

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

B：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竿滨。

C：full outer join：

全外連接：不僅包括符號連接表的匹配行佳恬，還包括兩個連接表中的所有記錄。

判斷對象是否存在

判斷數(shù)據(jù)庫是否存在

if exists (select * from sys.databases where name = ‘?dāng)?shù)據(jù)庫名’)

drop database [數(shù)據(jù)庫名]

判斷表是否存在

if not exists (select * from sysobjects where [name] = ‘表名’ and xtype=’U’)

begin

–這里創(chuàng)建表

end

判斷存儲過程是否存在

if exists (select * from sysobjects where id = object_id(N'[存儲過程名]’) and OBJECTPROPERTY(id, N’IsProcedure’) = 1)

drop procedure [存儲過程名]

判斷臨時表是否存在

if object_id(‘tempdb..#臨時表名’) is not null

drop table #臨時表名

判斷視圖是否存在

–SQL Server 2000

IF EXISTS (SELECT * FROM sysviews WHERE object_id = ‘[dbo].[視圖名]’

–SQL Server 2005

IF EXISTS (SELECT * FROM sys.views WHERE object_id = ‘[dbo].[視圖名]’

判斷函數(shù)是否存在

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[函數(shù)名]’) and xtype in (N’FN’, N’IF’, N’TF’))

drop function [dbo].[函數(shù)名]

獲取用戶創(chuàng)建的對象信息

SELECT [name],[id],crdate FROM sysobjects where xtype=’U’

/*

xtype 的表示參數(shù)類型于游，通常包括如下這些 C = CHECK 約束 D = 默認(rèn)值或 DEFAULT 約束 F = FOREIGN KEY 約束 L = 日志 FN = 標(biāo)量函數(shù) IF = 內(nèi)嵌表函數(shù) P = 存儲過程 PK = PRIMARY KEY 約束（類型是 K） RF = 復(fù)制篩選存儲過程 S = 系統(tǒng)表 TF = 表函數(shù) TR = 觸發(fā)器 U = 用戶表 UQ = UNIQUE 約束（類型是 K） V = 視圖 X = 擴展存儲過程 */

判斷列是否存在

if exists(select * from syscolumns where id=object_id(‘表名’) and name=’列名’)

alter table 表名 drop column 列名

判斷列是否自增列

if columnproperty(object_id(‘table’),’col’,’IsIdentity’)=1

print ‘自增列’

else

print ‘不是自增列’

SELECT * FROM sys.columns WHERE object_id=OBJECT_ID(‘表名’)

AND is_identity=1

判斷表中是否存在索引

if exists(select * from sysindexes where id=object_id(‘表名’) and name=’索引名’)

print ‘存在’

else

print ‘不存在

查看數(shù)據(jù)庫中對象

SELECT * FROM sys.sysobjects WHERE name=’對象名’

提升

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 1<>1

法二：select top 0 * into b from a

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;

跨數(shù)據(jù)庫之間表的拷貝

(具體數(shù)據(jù)使用絕對路徑) (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.MapPath(“.”&”\data.mdb” &”‘ where..

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)

顯示文章毁葱、提交人和最后回復(fù)時間

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

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

在線視圖查詢

(表名1：a

select * from (Select a,b,c FROM a) T where t.a > 1;

between的用法

between限制查詢數(shù)據(jù)范圍時包括了邊界值,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

in 的使用方法

select * from table1 where a [not] in (‘值1’,’值2’,’值4’,’值6’)

刪除主表中已經(jīng)在副表中沒有的信息

兩張關(guān)聯(lián)表delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1

四表聯(lián)查問題

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 …..

日程安排提前五分鐘提醒

SQL: select * from 日程安排 where datediff(‘minute’,f開始時間,getdate())>5

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

前10條記錄

select top 10 * form table1 where 范圍

選擇排名

選擇在每一組b值相同的數(shù)據(jù)中對應(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)

派生結(jié)果表

包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重復(fù)行而派生出一個結(jié)果表

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

隨機取出10條數(shù)據(jù)

select top 10 * from tablename order by newid()

隨機選擇記錄

select newid()

刪除重復(fù)記錄

Delete from tablename where id not in (select max(id) from tablename group by col1,col2,…)

列出數(shù)據(jù)庫里所有的表名

select name from sysobjects where type=’U’

列出表里的所有的

select name from syscolumns where id=object_id(‘TableName’)

列示排列

列示type、vender贰剥、pcs字段倾剿，以type字段排列，case可以方便地實現(xiàn)多重選擇，類似select 中的case前痘。

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’ 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 B 2

光盤 A 2

手機 B 3

手機 C 3

初始化表table1

TRUNCATE TABLE table1

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

數(shù)據(jù)類型轉(zhuǎn)換

declare @numid int

declare @id varchar(50)

set @numid=2005

set @id=convert(varchar,@numid)

通過上述語句完成數(shù)據(jù)類型Int轉(zhuǎn)換成varchar凛捏，其他轉(zhuǎn)換類似，可參看convert函數(shù)

技巧

1=1芹缔，1=2的使用

在SQL語句組合時用的較多

“where 1=1” 是表示選擇全部 “where 1=2”全部不選坯癣，

如：

if @strWhere !=’

begin

set @strSQL = ‘select count(*) as Total from [‘ + @tblName + ‘] where ‘ + @strWhere

end

else

begin

set @strSQL = ‘select count(*) as Total from [‘ + @tblName + ‘]’

end

我們可以直接寫成

set @strSQL = ‘select count(*) as Total from [‘ + @tblName + ‘] where 1=1 and ‘+ @strWhere

收縮數(shù)據(jù)庫

–重建索引

DBCC REINDEX

DBCC INDEXDEFRAG

–收縮數(shù)據(jù)和日志

DBCC SHRINKDB

DBCC SHRINKFILE

壓縮數(shù)據(jù)庫

dbcc shrinkdatabase(dbname)

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’

go

檢查備份集

RESTORE VERIFYONLY from disk=’E:\dvbbs.bak’

修復(fù)數(shù)據(jù)庫

Alter DATABASE [dvbbs] SET SINGLE_USER

GO

DBCC CHECKDB(‘dvbbs’,repair_allow_data_loss) WITH TABLOCK

GO

Alter DATABASE [dvbbs] SET MULTI_USER

GO

日志清除

SET NOCOUNT ON

DECLARE @LogicalFileName sysname,

@MaxMinutes INT,

@NewSize INT

USE tablename — 要操作的數(shù)據(jù)庫名

Select @LogicalFileName = ‘tablename_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 / initialize

DECLARE @OriginalSize int

Select @OriginalSize = size

FROM sysfiles

Where name = @LogicalFileName

Select ‘Original Size of ‘ + db_name() + ‘ LOG is ‘ +

CONVERT(VARCHAR(30),@OriginalSize) + ‘ 8K pages or ‘ +

CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + ‘MB’

FROM sysfiles

Where name = @LogicalFileName

Create 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_ONLY’

DBCC SHRINKFILE (@LogicalFileName, @NewSize)

EXEC (@TruncLog)

— Wrap the log if necessary.

WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) — time has not expired

AND @OriginalSize = (Select size FROM sysfiles Where name = @LogicalFileName)

AND (@OriginalSize * 8 /1024) > @NewSize

BEGIN — Outer loop.

Select @Counter = 0

WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000))

BEGIN — update

Insert DummyTrans VALUES (‘Fill Log’)

Delete DummyTrans

Select @Counter = @Counter + 1

END

EXEC (@TruncLog)

END

Select ‘Final Size of ‘ + db_name() + ‘ LOG is ‘ +

CONVERT(VARCHAR(30),size) + ‘ 8K pages or ‘ +

CONVERT(VARCHAR(30),(size*8/1024)) + ‘MB’

FROM sysfiles

Where name = @LogicalFileName

Drop TABLE DummyTrans

SET NOCOUNT OFF

更改某個表

exec sp_changeobjectowner ‘tablename’,’dbo’

存儲更改全部表

Create PROCEDURE dbo.User_ChangeObjectOwnerBatch

@OldOwner as NVARCHAR(128),

@NewOwner as NVARCHAR(128)

AS

DECLARE @Name as NVARCHAR(128)

DECLARE @Owner as NVARCHAR(128)

DECLARE @OwnerName as NVARCHAR(128)

DECLARE curObject CURSOR FOR

select 'Name' = name,

'Owner' = user_name(uid)

from sysobjects

where user_name(uid)=@OldOwner

order by name

OPEN curObject

FETCH NEXT FROM curObject INTO @Name, @Owner

WHILE(@@FETCH_STATUS=0)

BEGIN

if @Owner=@OldOwner

begin

set @OwnerName = @OldOwner + '.' + rtrim(@Name)

exec sp_changeobjectowner @OwnerName, @NewOwner

end– select @name,@NewOwner,@OldOwner

FETCH NEXT FROM curObject INTO @Name, @Owner

END

close curObject

deallocate curObject

GO

SQL SERVER中直接循環(huán)寫入數(shù)據(jù)

declare @i int

set @i=1

while @i<30

begin

insert into test (userid) values(@i)

set @i=@i+1

end