21.动态参数存储过程

--1. 使用 EXEC 实现的动态参数存储过程
CREATE PROC p_test
@para1 varchar(10)=null,
@para2 varchar(10)=null,
@para3 varchar(10)=null,
@para4 varchar(10)=null
AS
SET NOCOUNT ON
DECLARE @sql varchar(8000)
SET @sql='SELECT * FROM tbname WHERE 1=1'
IF @para1 IS NOT NULL
	SET @sql=@sql+' AND col1='''+@para1+''''
IF @para2 IS NOT NULL
	SET @sql=@sql+' AND col2='''+@para2+''''
IF @para3 IS NOT NULL
	SET @sql=@sql+' AND col3='''+@para3+''''
IF @para4 IS NOT NULL
	SET @sql=@sql+' AND col4='''+@para4+''''
EXEC(@sql)
GO


/*======================================================*/

--2. 使用 sp_executesql 实现的动态参数存储过程
CREATE PROC p_test
@para1 varchar(10)=null,
@para2 datetime=null,
@para3 varchar(10)=null,
@para4 int=null
AS
SET NOCOUNT ON
DECLARE @sql nvarchar(4000)
SET @sql='SELECT * FROM tbname WHERE 1=1'
	+CASE WHEN @para1 IS NULL THEN '' ELSE ' AND col1=@para1' END
	+CASE WHEN @para2 IS NULL THEN '' ELSE ' AND col2=@para2' END
	+CASE WHEN @para3 IS NULL THEN '' ELSE ' AND col3=@para3' END
	+CASE WHEN @para4 IS NULL THEN '' ELSE ' AND col4=@para4' END
EXEC sp_executesql @sql,N'
	@para1 varchar(10)=null,
	@para2 datetime=null,
	@para3 varchar(10)=null,
	@para4 int=null
',@para1,@para2,@para3,@para4
GO


/*======================================================*/

--3. 不使用动态 Transact-SQL 语句实现的动态参数存储过程
CREATE PROC p_test
@para1 varchar(10)=null,
@para2 datetime=null,
@para3 varchar(10)=null,
@para4 int=null
AS
SET NOCOUNT ON
SELECT * FROM tbname 
WHERE (@para1 IS NULL OR col1=@para1)
	AND (@para2 IS NULL OR col2=@para2)
	AND (@para3 IS NULL OR col3=@para3)
	AND (@para4 IS NULL OR col4=@para4)