创建数据库
创建之前判断该数据库是否存在
if exists (select * from sysdatabases where
name='databaseName')
drop database databaseName
go
Create DATABASE database-name
删除数据库
drop database dbname
备份
sql server
--- 创建 备份数据的 device
USE master
EXEC sp_addumpdevice 'disk', 'testBack',
'c:\mssql7backup\MyNwind_1.dat'
--- 开始 备份
BACKUP DATABASE pubs TO testBack
创建新表
create table tabname(col1 type1 [not null]
[primary key],col2 type2 [not null],..)
根据已有的表创建新表:
A:create table tab_new like tab_old
(使用旧表创建新表)
B:create table tab_new as select col1,col2…
from tab_old definition only
创建序列
create
sequence SIMON_SEQUENCE
minvalue 1 -- 最小值
maxvalue 999999999999999999999999999 最大值
start with 1 开始值
increment by 1 每次加几
cache 20;
删除新表
drop table tabname
增加一个列
Alter table tabname
add column col type
注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加
varchar类型的长度。
添加主键
Alter table tabname add
primary key(col)
说明:删除主键: Alter table tabname drop primary
key(col)
创建索引
create [unique] index idxname
on tabname(col….)
删除索引:drop index idxname on tabname
注:索引是不可更改的,想更改必须删除重新建。
创
建视图
create view viewname as select statement
删除视图:drop view viewname
几
个简单的基本的sql语句
选择:select * from table1 where 范围
插入:insert into table1(field1,field2)
values(value1,value2)
删除:delete from table1 where 范围
更新:update table1 set field1=value1 where 范围
查找:select * from table1 where field1 like
’%value1%’ (所有包含‘value1’这个模式的字符串)---like的语法很精妙,查资料!
排序:select * from table1 order by
field1,field2 [desc]
总数: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
最小:select min(field1) as minvalue from
table1[separator]
几个高级查询运算词
A: UNION 运算符
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和
TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION
ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。
B: EXCEPT 运算符
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2
中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。
C: INTERSECT 运算符
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2
中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。
注:使用运算词的几个查询结果行必须是一致的。
使
用外连接
A、left outer join:
左外连接(左连接):结果集既包括连接表的匹配行,也包括左连接表的所有行。
SQL: select a.a, a.b, a.c, b.c, b.d, b.f
from a LEFT OUT JOIN b ON a.a = b.c
B:right outer join:
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。
C:full outer join:
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。
[]
提升复制表
(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
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;
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..
子查询
(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)
显
示文章、提交人和最后回复时间
select a.title,a.username,b.adddate from table
a,(select max(adddate) adddate from table where table.title=a.title) b
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
在线视图查询
(表名1:a
select * from (Select a,b,c FROM a) T where
t.a > 1;
between的用法
between限制查询数据范围时包括了边界
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 数值1 and 数值2
in 的使用方法
select * from
table1 where a [not] in (‘值1’,’值2’,’值4’,’值6’)
删除主表
中已经在副表中没有的信息
两张关联表delete from table1 where not exists ( select *
from table2 where table1.field1=table2.field1
四表联查
问题
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
安排提前五分钟提醒
SQL: select * from 日程安排 where
datediff('minute',f开始时间,getdate())>5
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
前10条记录
select top 10 * form table1 where 范围
选择排名
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)
派
生结果表
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)
随机取出10条数据
select top 10 * from tablename order by newid()
随
机选择记录
select newid()
删除重复记录
Delete
from tablename where id not in (select max(id) from tablename group by
col1,col2,...)
列出数据库里所有的表名
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、pcs字段,以type字段排列,case可以方便地实现多重选择,类似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' then pcs else 0 end) FROM tablename group by type
显示结果:
type vender pcs
电脑 A 1
电脑 A 1
光盘 B 2
光盘 A 2
手机 B 3
手机 C 3
初始化表table1
TRUNCATE TABLE table1
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
数据类型转换
declare @numid int
declare @id varchar(50)
set @numid=2005
set @id=convert(varchar,@numid)
通过上述语句完成数据类型Int转换成varchar,其他转换类似,可参看convert函
数
[]
技巧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
收缩数据库
--重建索引
DBCC REINDEX
DBCC INDEXDEFRAG
--收缩数据和日志
DBCC SHRINKDB
DBCC SHRINKFILE
压缩数据库
dbcc shrinkdatabase(dbname)
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
检查备份集
RESTORE
VERIFYONLY from disk='E:\dvbbs.bak'
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
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
更改某个表
exec sp_changeobjectowner 'tablename','dbo'
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
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