表值可选参数

Question

Is it possible to create a procedure with a table value parameter as an optional parameter.

I tried the following code:

CREATE PROCEDURE SP
@Table testteype = null READONLY
AS 
....

But I get this error:

Operand type clash: void type is incompatible with test type 

ps: I use sql server with C#.Net

Answer 1

Table-Valued parameters always have an implicit value of an empty table. So you can actually call that procedure without any parameters and it would execute but the table would be empty.

So it doesn't really make sense to label a table-value parameter with a default value. Remove the "=null", check the table contents, and you should be good to go.

Answer 2

Basically, having default value "= null" makes no sense and is the reason of the error.

By default, @Table testteype gets value of an empty table. Thus, you may remove = null:

CREATE PROCEDURE SP
@Table testteype  READONLY
AS 
....

Reference: for a sample on how to use this with C# ADO.NET i would recommend to use this post - Using SQL Server's Table Valued Parameters

Answer 3

--exa:
--create TYPE  Table_tt   as table(id int,name  varchar(10))

create table #a  (aid int,price int)
insert into #a (aid  ,price  )
select 1,10
union
select 2,50

create PROCEDURE SP
@Table_tt Table_tt  null READONLY     
AS 
 begin 
 select * into #tem from @Table_tt
 select * from #a where aid in(select id from #tem)  or aid='' 
 end

 exec SP 

Answer 4

Not sure why the answer above states making default value = NULL is incorrect but this works for me.

CREATE PROCEDURE SP
(
    @Param1 VARCHAR(10),
    @Param2 VARCHAR(10)=NULL
)

SELECT......
WHERE @Param1 = SOMETHING
AND (@Param2 = SOMETHING OR @Param2 IS NULL)