SQL 函数、存储过程、游标与事务模板

1.标量函数：结果为一个单一的值，可包含逻辑处理过程。其中不能用getdate()之类的不确定性系统函数.

--标量值函数

-- ================================================

-- Template generated from Template Explorer using:

-- Create Scalar Function (New Menu).SQL

--

-- Use the Specify Values for Template Parameters 

-- command (Ctrl-Shift-M) to fill in the parameter 

-- values below.

--

-- This block of comments will not be included in

-- the definition of the function.

-- ================================================

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

-- =============================================

-- Author:   <Author,,Name>

-- Create date: <Create Date, ,>

-- Description: <Description, ,>

-- =============================================

CREATE FUNCTION <Scalar_Function_Name, sysname, FunctionName> 

(

-- Add the parameters for the function here

<@Param1, sysname, @p1> <Data_Type_For_Param1, , int>

)

RETURNS <Function_Data_Type, ,int>

AS

BEGIN

-- Declare the return variable here

DECLARE <@ResultVar, sysname, @Result> <Function_Data_Type, ,int>



-- Add the T-SQL statements to compute the return value here

SELECT <@ResultVar, sysname, @Result> = <@Param1, sysname, @p1>



-- Return the result of the function

RETURN <@ResultVar, sysname, @Result>



END

2.内联表值函数:返回值为一张表,仅通过一条SQL语句实现,没有逻辑处理能力.可执行大数据量的查询.

--内联表值函数



-- ================================================

-- Template generated from Template Explorer using:

-- Create Inline Function (New Menu).SQL

--

-- Use the Specify Values for Template Parameters 

-- command (Ctrl-Shift-M) to fill in the parameter 

-- values below.

--

-- This block of comments will not be included in

-- the definition of the function.

-- ================================================

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

-- =============================================

-- Author:   <Author,,Name>

-- Create date: <Create Date,,>

-- Description: <Description,,>

-- =============================================

CREATE FUNCTION <Inline_Function_Name, sysname, FunctionName> 

( 

-- Add the parameters for the function here

<@param1, sysname, @p1> <Data_Type_For_Param1, , int>, 

<@param2, sysname, @p2> <Data_Type_For_Param2, , char>

)

RETURNS TABLE 

AS

RETURN 

(

-- Add the SELECT statement with parameter references here

SELECT 0

)

GO

3.多语句表值函数:返回值为一张表,有逻辑处理能力,但仅能对小数据量数据有效,数据量大时,速度很慢.

--多语句表值函数



-- ================================================

-- Template generated from Template Explorer using:

-- Create Multi-Statement Function (New Menu).SQL

--

-- Use the Specify Values for Template Parameters 

-- command (Ctrl-Shift-M) to fill in the parameter 

-- values below.

--

-- This block of comments will not be included in

-- the definition of the function.

-- ================================================

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

-- =============================================

-- Author:   <Author,,Name>

-- Create date: <Create Date,,>

-- Description: <Description,,>

-- =============================================

CREATE FUNCTION <Table_Function_Name, sysname, FunctionName> 

(

-- Add the parameters for the function here

<@param1, sysname, @p1> <data_type_for_param1, , int>, 

<@param2, sysname, @p2> <data_type_for_param2, , char>

)

RETURNS 

<@Table_Variable_Name, sysname, @Table_Var> TABLE 

(

-- Add the column definitions for the TABLE variable here

<Column_1, sysname, c1> <Data_Type_For_Column1, , int>, 

<Column_2, sysname, c2> <Data_Type_For_Column2, , int>

)

AS

BEGIN

-- Fill the table variable with the rows for your result set



RETURN 

END

GO

4.游标:对多条数据进行同样的操作.如同程序的for循环一样.有几种循环方向控制,一般用FETCH Next.

--示意性SQL脚本



DECLARE @MergeDate Datetime 

DECLARE @MasterId Int 

DECLARE @DuplicateId Int 



SELECT @MergeDate = GetDate() 





DECLARE merge_cursor CURSOR FAST_FORWARD FOR SELECT MasterCustomerId, DuplicateCustomerId FROM DuplicateCustomers WHERE IsMerged = 0 

--定义一个游标对象[merge_cursor]

--该游标中包含的为:[SELECT MasterCustomerId, DuplicateCustomerId FROM DuplicateCustomers WHERE IsMerged = 0 ]查询的结果.



OPEN merge_cursor 

--打开游标

FETCH NEXT FROM merge_cursor INTO @MasterId, @DuplicateId 

--取数据到临时变量

WHILE @@FETCH_STATUS = 0 --系统@@FETCH_STATUS = 0 时循环结束

--做循环处理

BEGIN 

EXEC MergeDuplicateCustomers @MasterId, @DuplicateId 



UPDATE DuplicateCustomers 

SET 

IsMerged = 1, 

MergeDate = @MergeDate 

WHERE 

MasterCustomerId = @MasterId AND 

DuplicateCustomerId = @DuplicateId 



FETCH NEXT FROM merge_cursor INTO @MasterId, @DuplicateId 

--再次取值

END 



CLOSE merge_cursor 

--关闭游标

DEALLOCATE merge_cursor 

--删除游标

[说明:游标使用必须要配对,Open--Close,最后一定要记得删除游标.]

5.事务:当一次处理中存在多个操作,要么全部操作,要么全部不操作,操作失败一个,其他的就全部要撤销,不管其他的是否执行成功,这时就需要用到事务.

begin tran

update tableA

set columnsA=1,columnsB=2

where RecIs=1

if(@@ERROR <> 0 OR @@ROWCOUNT <> 1)

begin

rollback tran

raiserror( '此次update表tableA出错!!' , 16 , 1 ) 

return

end



insert into tableB (columnsA,columnsB) values (1,2)

if(@@ERROR <> 0 OR @@ROWCOUNT <> 1)

begin

rollback tran

raiserror( '此次update表tableA出错!!' , 16 , 1 ) 

return

end



end

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