MSSQL 存储过程实现更新，如果要更新的字段内容为空，则该字段不作变更，只更新其他字段

一项目有这个需求，顺便将代码贴上，共同学习。

/****** 定义输入参数 ******/
ALTER proc [dbo].[upkeywords]
@inkeyval  nvarchar(100),
@inkeycompete  int,
@inkeyinclude  int,
@inKeyID int

as

DECLARE
/****** 定义变量 ******/
@keyval nvarchar(100),
@keycompete int,
@keyinclude int,
@KeyID int
/****** 给变量赋原来的值 ******/
set @keyval=(select KeyVal from Keywords where KeyID=@inKeyID)
set @keycompete=(select keycompete from Keywords where KeyID=@inKeyID)
set @keyinclude=(select keyinclude from Keywords where KeyID=@inKeyID)

/****** 如果传入的参数是NULL，就将原来的值还给它 ******/
update Keywords set 
KeyVal=ISNULL(@inkeyval,@keyval),
keycompete=ISNULL(@inkeycompete,@keycompete),
keyinclude=ISNULL(@inkeyinclude,@keyinclude)
where KeyID=@inKeyID