SQL经典语句和要点整理

*SQL中的保留关键字

action add aggregate all alter after and as asc avg avg_row_length auto_increment between bigint bit binary blob bool both by cascade case char character

change check checksum column columns comment constraint create cross current_date current_time current_timestamp data database databases date datetime day day_hour day_minute

day_second dayofmonth dayofweek dayofyear dec decimal default delayed delay_key_write delete desc describe distinct distinctrow double drop

*得出SQL语句的执行时间的方法

例如:

declare @d datetime

set @d=getdate() select * from ycdata1 select [alltime]=datediff(ms,@d,getdate())

红色为我们要执行的sql语句,结果为 执行花费时间

*清空数据库中所有表的数据(已经测试过,可以正常运行)

declare crsr cursor

for SELECT [name] FROM DBO.SYSOBJECTS

WHERE OBJECTPROPERTY(ID,N'IsTable')=1 and type = 'U' and [name] <> 'dtproperties' --and crdate...

open crsr

declare @tblName sysname

fetch crsr into @tblName

EXEC('truncate table '+@tblName)

while @@fetch_status=0

fetch next from crsr into @tblName

EXEC('truncate table '+@tblName)

close crsr

deallocate crsr //--删除以释放游标//可以为crdate字段指定表的创建日期

*常用SQL语句扩展和例子

一 数据库筛选记录:

SQL= select * from tb1 where field1 =’value1’ order by id desc

Select * from tb1 where field1 like ‘% value1%’ order by id desc

Select top 10 * from tb1 where field1 =’ value1’ order by id,age desc

Select * from tb1 where field1 in(‘value1’, ‘value2’, ‘value3’,)

Select * from tb1 where field1 between value1 and value2

select * from tb1, tb2 where tb1.id *= tb2.id

select a,b,c from tb1 where a IN (select d from b ) //子查询

select * from tb1 where id not in(select id from tb1 where 表达式) order by id desc

更多:

说明：两张关联表，删除主表中已经在副表中没有的信息

delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 )

说明：Distinct查询数据库存表内不重复的记录

Select Distinct field1 From tb1

说明：count函数,查询数库表内有多少条记录，“field1”是指同一字段

"Select Count(*) From tb1 where field1>#18:0:0# and field1< #19:00# "

说明：两张关联表，删除主表中已经在副表中没有的信息

delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 )

说明：复制表(只复制结构,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

说明：拷贝表(拷贝数据,源表名：a 目标表名：b) (Access可用)

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

说明：跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用)

insert into b(a, b, c) select d,e,f from b in ‘具体数据库’ where 条件

例子：..from b in '"&Server.MapPath(".")&""data.mdb" &"' where..

说明：外连接查询(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

说明：日程安排提前五分钟提醒

SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5

说明：选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.)

select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b)

说明：包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表

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

说明：列出数据库里所有的表名

select name from sysobjects where type='U'

说明：选择从10到15的记录

select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc

说明：一条sql 语句搞定数据库分页

select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段

二 数据库更新记录

sql= update tb1set field1=字段值 where 条件表达式

update tb1 set field1= value1, field2= value2……fieldn= valuen where条件表达式

三 删除记录

sql= deletefrom tb1 where 条件表达式

deletefrom tb1" //(将数据表所有记录删除)

四 添加记录

sql=insertinto数据表(field1, field1, field2…)values(value1, value2, value3…)"

insertinto目标数据表select*from源数据表"(把源数据表的记录添加到目标数据表)

五 统计等

AVG(字段名)得出一个表格栏平均值

COUNT(*|字段名)对数据行数的统计或对某一栏有值的数据行数统计

MAX(字段名)取得一个表格栏最大的值

MIN(字段名)取得一个表格栏最小的值

SUM(字段名)把数据栏的值相加

引用以上函数的方法：

sql="select sum(filed) as 别名from 数据表where条件表达式" //返回一个统计值

六 建立表和创建表

CREATETABLE tb1 filed1类型1(长度), filed1 类型2(长度)……)

例：CREATETABLEtab01 (namevarchar (50), datetimedefaultnow ())

DROPTABLE数据表名称(永久性删除一个数据表)

七 创建数据库

CREATE DATABASE database-name

八 删除数据库

drop database dbname

*其它技巧

1、1=1，1=2的使用，在SQL语句组合时用的较多

“where 1=1” 是表示选择全部 “where 1=2”全部不选，

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

我们可以直接写成

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

2、收缩数据库

--重建索引

DBCC REINDEX

DBCC INDEXDEFRAG

--收缩数据和日志

DBCC SHRINKDB

DBCC SHRINKFILE

3、压缩数据库

dbcc shrinkdatabase(dbname)

4、转移数据库给新用户以已存在用户权限

exec sp_change_users_login 'update_one','newname','oldname'

go

5、检查备份集

RESTORE VERIFYONLY from disk='E:"dvbbs.bak'

6、修复数据库

ALTER DATABASE [dvbbs] SET SINGLE_USER

GO

DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK

GO

ALTER DATABASE [dvbbs] SET MULTI_USER

GO

7、日志清除

SET NOCOUNT ON

DECLARE @LogicalFileName sysname,

@MaxMinutes INT,

@NewSize INT

USE tablename -- 要操作的数据库名

SELECT @LogicalFileName = 'tablename_log', -- 日志文件名

@MaxMinutes = 10, -- Limit on time allowed to wrap log.

@NewSize = 1 -- 你想设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

8、说明：更改某个表

exec sp_changeobjectowner 'tablename','dbo'

9、存储更改全部表

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

10、SQL SERVER中直接循环写入数据

declare @i int

set @i=1

while @i<30

begin

insert into test (userid) values(@i)

set @i=@i+1

end