SQL 函数、存储过程、游标与事务模板

--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.

--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
commit