文章摘要
以下是关于SQL Server存储过程与函数的简要总结，涵盖了文章中的核心内容：
### SQL Server存储过程与函数总结
1. **存储过程基本语法**
- **带输入参数的存储过程**：使用`@`符号接收参数，用于接收外部数据，如`@commentid int`。
```sql
create proc GetComment
(@commentid int)
as
select * from Comment where CommentID=@commentid
```
- **输入与输出参数的存储过程**：使用`@`接收输入参数，并通过`@`输出结果。
```sql
create proc GetCommentCount
(@newsid int, @count int output)
as
select @count=count(*) from Comment where NewsID=@newsid
```
- **返回单个值的函数**：接收参数后返回计算结果。
```sql
create function MyFunction
(@newsid int)
returns int
as
begin
declare @count int
select @count=count(*) from Comment where NewsID=@newsid
return @count
end
```
- **返回值为表的函数**：直接返回一个结果集。
```sql
create function GetFunctionTable
(@newsid int)
returns table
as
return
( select * from Comment where NewsID=@newsid )
```
2. **不拼接SQL字符串实现多条件查询**
- **传统拼接方法**：易出错，且不推荐。
```sql
set @sql=' select * from table where 1=1 '
if (@addDate is not null)
set @sql=@sql+' and addDate='+ @addDate + ' '
...
exec(@sql)
```
- **解决方案**：
- 直接写入条件：
```sql
select * from table where addDate=... and name=...
```
- 使用`CASE`语句合并条件：
```sql
select * from table where
addDate=CASE @addDate IS NULL THEN addDate ELSE @addDate END,
name=CASE @name WHEN '' THEN name ELSE @name END
```
3. **SQL Server存储过程与函数应用**
- **变量**：包括简单赋值、使用SELECT语句赋值和更新语句赋值。
```sql
declare @a int
set @a=5
print @a
declare @user1 nvarchar(50)
select @user1='张三'
print @user1
declare @user2 nvarchar(50)
select @user2=Name from ST_User where ID=1
print @user2
```
- **临时表、表变量与游标**：用于处理中间数据和高效查询。
```sql
-- 创建临时表
create table #DU_User1
(
[ID] [ int ] NOT NULL ,
[Oid] [ int ] NOT NULL ,
[Login] [nvarchar](50) NOT NULL ,
[Rtx] [nvarchar](4) NOT NULL ,
[ Name ] [nvarchar](5) NOT NULL ,
[ Password ] [nvarchar]( max ) NULL ,
[State] [nvarchar](8) NOT NULL
);
-- 插入并查询
insert into #DU_User2 from ST_User where ID<8
select * from #DU_User2 where ID<3 union select * from #DU_User1
drop table #DU_User1
drop table #DU_User2
-- �游标实现
declare @ID int
declare @Oid int
declare @Login varchar(50)
declare user_cur cursor for select ID,Oid,[Login] from ST_User
open user_cur
while @@fetch_status=0
begin
fetch next from user_cur into @ID,@Oid,@Login
print @ID
end
close user_cur
deallocate user_cur
-- 打造游标
declare @ID INT
declare @Oid INT
declare @Login NVARCHAR(50)
declare user_cur cursor for select ID,Oid,[Login] from ST_User
open user_cur
while @@fetch_status=0
begin
fetch next from user_cur into @ID,@Oid,@Login
print @ID
end
close user_cur
deallocate user_cur
```
4. **触发器**
- **定义与使用**：用于执行操作前的检查和记录。
```sql
create trigger User_OnUpdate
on ST_User
for Update
as
declare @msg nvarchar(50)
select @msg=N '姓名从“' + Deleted. Name + '”修改为“' + Inserted. Name + '”
from Inserted,Deleted
insert into [LOG](MSG) values (@msg)
drop trigger User_OnUpdate
```
5. **存储过程与函数应用示例**
- **创建带输出参数的存储过程**：
```sql
create proc PR_Sum
@a int,
@b int,
@sum int output
as
begin
set @sum=@a+@b
end
```
- **调用存储过程**：
```sql
declare @mysum int
execute PR_Sum 1,2,@mysum output
print @mysum
```
- **自定义函数示例**：
```sql
create function FUNC_UserTab_1
(
@myId int
)
returns table
as
return ( select * from ST_User where ID<@myId )
```
6. **注意事项**
- 使用`CASE`语句合并条件，减少拼接SQL字符串。
- 定义变量和函数，封装业务逻辑，提高复用性和可维护性。
- 使用游标和临时表优化查询性能，避免一次性查询大结果集。
通过以上总结，可以更好地理解和应用SQL Server存储过程和函数，避免传统拼接字符串的缺陷，提升代码质量和效率。
–有输入参数的存储过程–
create proc GetComment
(@commentid int)
as
select * from Comment where CommentID=@commentid
–有输入与输出参数的存储过程–
create proc GetCommentCount
@newsid int,
@count int output
as
select @count=count(*) from Comment where NewsID=@newsid
–返回单个值的函数–
create function MyFunction
(@newsid int)
returns int
as
begin
declare @count int
select @count=count(*) from Comment where NewsID=@newsid
return @count
end
–调用方法–
declare @count int
exec @count=MyFunction 2
print @count
–返回值为表的函数–
Create function GetFunctionTable
(@newsid int)
returns table
as
return
(select * from Comment where NewsID=@newsid)
–返回值为表的函数的调用–
select * from GetFunctionTable(2)
SQLServer 存储过程中不拼接SQL字符串实现多条件查询
–以前拼接的写法
set @sql=’ select * from table where 1=1 ‘
if (@addDate is not null)
set @sql=@sql+’ and addDate=’+ @addDate + ‘ ‘
if (@name <>” and is not null)
set @sql=@sql+ ‘ and name=’ + @name + ‘ ‘
exec(@sql)
下面是 不采用拼接SQL字符串实现多条件查询的解决方案
–第一种写法是 感觉代码有些冗余
if (@addDate is not null) and (@name <> ”)
select * from table where addDate=@addDate and name=@name
else if (@addDate is not null) and (@name=”)
select * from table where addDate=@addDate
else if(@addDate is null) and (@name <> ”)
select * from table where and name=@name
else if(@addDate is null) and (@name=”)
select * from table
–第二种写法是
select * from table where (addDate=@addDate or @addDate is null) and (name=@name or @name=”)
–第三种写法是
SELECT * FROM table where
addDate=CASE @addDate IS NULL THEN addDate ELSE @addDate END,
name=CASE @name WHEN ” THEN name ELSE @name END
SQLSERVER存储过程基本语法
一、定义变量
–简单赋值
declare @a int
set @a=5
print @a
–使用select语句赋值
declare @user1 nvarchar(50)
select @user1=’张三’
print @user1
declare @user2 nvarchar(50)
select @user2=Name from ST_User where ID=1
print @user2
–使用update语句赋值
declare @user3 nvarchar(50)
update ST_User set @user3=Name where ID=1
print @user3
二、表、临时表、表变量
–创建临时表1
create table #DU_User1
(
[ID] [ int ] NOT NULL ,
[Oid] [ int ] NOT NULL ,
[Login] [nvarchar](50) NOT NULL ,
[Rtx] [nvarchar](4) NOT NULL ,
[ Name ] [nvarchar](5) NOT NULL ,
[ Password ] [nvarchar]( max ) NULL ,
[State] [nvarchar](8) NOT NULL
);
–向临时表1插入一条记录
insert into #DU_User1 (ID,Oid,[Login],Rtx, Name ,[ Password ],State) values (100,2, ‘LS’ , ‘0000’ , ‘临时’ , ‘321’ , ‘特殊’ );
–从ST_User查询数据，填充至新生成的临时表
select * into #DU_User2 from ST_User where ID<8
–查询并联合两临时表
select * from #DU_User2 where ID<3 union select * from #DU_User1
–删除两临时表
drop table #DU_User1
drop table #DU_User2
–创建临时表
CREATE TABLE #t
(
[ID] [ int ] NOT NULL ,
[Oid] [ int ] NOT NULL ,
[Login] [nvarchar](50) NOT NULL ,
[Rtx] [nvarchar](4) NOT NULL ,
[ Name ] [nvarchar](5) NOT NULL ,
[ Password ] [nvarchar]( max ) NULL ,
[State] [nvarchar](8) NOT NULL ,
)
–将查询结果集（多条数据）插入临时表
insert into #t select * from ST_User
–不能这样插入
–select * into #t from dbo.ST_User
–添加一列，为int型自增长子段
alter table #t add [myid] int NOT NULL IDENTITY(1,1)
–添加一列，默认填充全球唯一标识
alter table #t add [myid1] uniqueidentifier NOT NULL default (newid())
select * from #t
drop table #t
–给查询结果集增加自增长列
–无主键时：
select IDENTITY( int ,1,1) as ID, Name ,[Login],[ Password ] into #t from ST_User
select * from #t
–有主键时：
select ( select SUM (1) from ST_User where ID<=a.ID) as myID,* from ST_User a order by myID
–定义表变量
declare @t table
(
id int not null ,
msg nvarchar(50) null
)
insert into @t values (1, ‘1’ )
insert into @t values (2, ‘2’ )
select * from @t
三、循环
–while循环计算1到100的和
declare @a int
declare @ sum int
set @a=1
set @ sum=0
while @a<=100
begin
set @ sum +=@a
set @a+=1
end
print @ sum
四、条件语句
–if,else条件分支
if(1+1=2)
begin
print ‘对’
end
else
begin
print ‘错’
end
–when then条件分支
declare @today int
declare @week nvarchar(3)
set @today=3
set @week=case
when @today=1 then ‘星期一’
when @today=2 then ‘星期二’
when @today=3 then ‘星期三’
when @today=4 then ‘星期四’
when @today=5 then ‘星期五’
when @today=6 then ‘星期六’
when @today=7 then ‘星期日’
else ‘值错误’
end
print @week
五、游标
declare @ID int
declare @Oid int
declare @Login varchar (50)
–定义一个游标
declare user_cur cursor for select ID,Oid,[Login] from ST_User
–打开游标
open user_cur
while @@fetch_status=0
begin
–读取游标
fetch next from user_cur into @ID,@Oid,@Login
print @ID
–print @Login
end
close user_cur
–摧毁游标
deallocate user_cur
五、游标
declare @ID int
declare @Oid int
declare @Login varchar (50)
–定义一个游标
declare user_cur cursor for select ID,Oid,[Login] from ST_User
–打开游标
open user_cur
while @@fetch_status=0
begin
–读取游标
fetch next from user_cur into @ID,@Oid,@Login
print @ID
–print @Login
end
close user_cur
–摧毁游标
deallocate user_cur
六、触发器
触发器中的临时表：
Inserted
存放进行insert和update 操作后的数据
Deleted
存放进行delete 和update操作前的数据
–创建触发器
Create trigger User_OnUpdate
On ST_User
for Update
As
declare @msg nvarchar(50)
–@msg记录修改情况
select @msg=N ‘姓名从“’ + Deleted. Name + N ‘”修改为“’ + Inserted. Name + ‘”’ from Inserted,Deleted
–插入日志表
insert into [LOG](MSG) values (@msg)
–删除触发器
drop trigger User_OnUpdate
七、存储过程
–创建带output参数的存储过程
CREATE PROCEDURE PR_Sum
@a int ,
@b int ,
@ sum int output
AS
BEGIN
set @ sum=@a+@b
END
–创建Return返回值存储过程
CREATE PROCEDURE PR_Sum2
@a int ,
@b int
AS
BEGIN
Return @a+@b
END
–执行存储过程获取output型返回值
declare @mysum int
execute PR_Sum 1,2,@mysum output
print @mysum
–执行存储过程获取Return型返回值
declare @mysum2 int
execute @mysum2=PR_Sum2 1,2
print @mysum2
八、自定义函数
函数的分类：
1）标量值函数
2）表值函数
a:内联表值函数
b:多语句表值函数
3）系统函数
–新建标量值函数
create function FUNC_Sum1
(
@a int ,
@b int
)
returns int
as
begin
return @a+@b
end
–新建内联表值函数
create function FUNC_UserTab_1
(
@myId int
)
returns table
as
return ( select * from ST_User where ID<@myId)
–新建多语句表值函数
create function FUNC_UserTab_2
(
@myId int
)
returns @t table
(
[ID] [ int ] NOT NULL ,
[Oid] [ int ] NOT NULL ,
[Login] [nvarchar](50) NOT NULL ,
[Rtx] [nvarchar](4) NOT NULL ,
[ Name ] [nvarchar](5) NOT NULL ,
[ Password ] [nvarchar]( max ) NULL ,
[State] [nvarchar](8) NOT NULL
)
as
begin
insert into @t select * from ST_User where ID<@myId
return
end
–调用表值函数
select * from dbo.FUNC_UserTab_1(15)
–调用标量值函数
declare @s int
set @s=dbo.FUNC_Sum1(100,50)
print @s
–删除标量值函数
drop function FUNC_Sum1
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