将Null值插入整数列

Question

Through the front end I want to insert NULL value to the Column whose DataType is Int.

I used like this:

POP.JobOrderID = Convert.ToInt32(DBNull.Value);

But I cannot Insert Null value, it throws error such as "Object cannot be cast from DBNull to other types":

How to insert NULL values?

Answer 1

if you wish to do it POP.JobOrderID should be type int? ( nullable int) not int

Answer 2

kleinohad is correct. Furthermore, you should assign null , not DBNull.Value

Answer 3

Use Nullable<Int32> or just an alias: int? .

POP.JobOrderID = 5;
// or
POP.JobOrderID = null;

Usage in ADO.NET:

command.Parameters.AddWithValue("@JobOrderId", POP.JobOrderID ?? DBNull.Value);

which is equals to:

POP.JobOrderID.HasValue ? POP.JobOrderID.Value : DBNull.Value;

Answer 4

This

   POP.JobOrderID = new Nullable<Int32>();

should work too IF the JobOrderID is a nullable type ( int? ).

Cheers

Answer 5

Like this:

 POP.JobOrderID = null;    // JobOrderID should be of type int? which is a nullable-int

Hope that helps.