通过Nullable整数(int ?SomeValue = NULL)作为存储过程的参数。

I'm trying to create a stored procedure that would take 4 paramters. These 4 paramters dictate how the returned table will look like.

我要创建一个存储过程，它需要4个参数。这4个参数决定返回的表是什么样子。

@C_ID parameter is always numeric. @U_ID and @P_ID values can contain a valid numeric value, or can be (or should be) passed as NULL so WHERE conditions either execute or not.

@C_ID参数总是数值型的。@U_ID和@P_ID值可以包含一个有效的数值，或者可以(或应该)作为NULL传递，以便执行或不执行条件。

ALTER PROCEDURE [dbo].[GetData]
    @C_ID integer,
    @U_ID integer = Null,
    @P_ID integer = Null,
    @SortIndex integer = 1
AS 
BEGIN
    SELECT
        ID, P_ID, U_Name, P_Name, 
        FORMAT(Date_When, 'dd/MM/yyyy hh:mm tt')
    FROM 
        SomeTable
    WHERE 
        C_ID = @C_ID 
        AND (@P_ID IS NULL OR P_ID = @P_ID) 
        AND (@U_ID IS NULL OR U_ID = @U_ID)
   ORDER BY 
        CASE WHEN @SortIndex = 1 THEN -ID 
             ELSE ID 
        END ASC
END

On SQL Server 2014 the following executions work fine without any errors:

在SQL Server 2014上，以下的执行工作正常，没有任何错误:

exec GetData '15', null, null, '1';
exec GetData '15', '1', null, '1';
exec GetData '15', null, '1', '1';
exec GetData '15', '1', '1', '1';
...

However on C# side the following code fails to execute:

但是在c#端，以下代码没有执行:

int? SomeValue = null;
Adapter = new SqlDataAdapter("exec GetData '15'," + SomeValue + ",null,'1';", Connection);
Adapter.Fill(Data);

which gives me an error

这会给我一个错误

Incorrect syntax near ','.

不正确的语法”、“附近。

If I change the SomeValue variable to 1, it works perfectly fine.

如果我将SomeValue变量更改为1，它会很好地工作。

DBNull.Value and simply leaving the parameter as ' ' do not work either.

DBNull。值并简单地将参数保留为' '也不起作用。

So the question would be: how would I (if it is possible) be able to pass nullable integer to SQL given that it can be both null and a valid number?

所以问题是:如果可能的话，我如何将可空整数传递给SQL，因为SQL既可以是null，也可以是一个有效的数字?

2 个解决方案

#1

Do something along those lines:

做一些类似的事情:

Adapter = new SqlDataAdapter();

//con is an open SQLConnection
var cmd = new SQLCommand("GetData", con);
cmd.Parameters.Add(new SqlParameter("@C_ID", 15));
cmd.Parameters.Add(new SqlParameter("@U_ID", SomeValue ?? DBNull.Value));
cmd.Parameters.Add(new SqlParameter("@P_ID", SomeValue ?? DBNull.Value));
cmd.Parameters.Add(new SqlParameter("@SortIndex", 1));
cmd.CommandType = CommandType.StoredProcedure;
Adapter.SelectCommand = cmd;
Adapter.Fill(Data);

The ?? is called the null-coalescing operator and checks if SomeValue is null. If so, the value behind the ?? is used - in your case DBNull.Value.

的? ?被称为null-coalescing运算符，检查SomeValue是否为null。如果是，那么?在您的案例DBNull.Value中。

And as GSerg already pointed out, always keep Little Bobby Tables in the back of your head.

正如GSerg已经指出的，永远在你的后脑勺上放一个小博比表。

Edit: Null-coalescing reference

编辑:空合并参考

#2

Did you tried something like below?

你试过以下的方法吗?

SomeValue ?? "null"

#1