Inserting NULL to SQL DB from C# DbCommand

Question

        DbParameter param = comm.CreateParameter();
        param = comm.CreateParameter();
        param.ParameterName = "@StaffId";
        if (!string.IsNullOrEmpty(activity.StaffId))
            param.Value = activity.StaffId;
        param.DbType = DbType.String;
        comm.Parameters.Add(param);

The above does not work (obviously), object not instantiated. I am attempting to insert a NULL into the database when StaffId is NOT populated. How can I achieve this?

Perfect! If you post this as answer I'll mark it as correct. — SkonJeet, Mar 21 '12 at 09:27
As for why... http://stackoverflow.com/questions/4488727/what-is-the-point-of-dbnull/9632050#9632050 — Marc Gravell, Mar 21 '12 at 09:33

Andrey Gurinov · Accepted Answer · 2012-03-21T09:43:25.730

47

You can use DBNull.Value when you need to pass NULL as a parameter to the stored procedure.

param.Value = DBNull.Value;

Or you can use that instead of your if operator:

param.Value = !string.IsNullOrEmpty(activity.StaffId) ? activity.StaffId : (object)DBNull.Value;

edited Mar 21 '12 at 09:43

answered Mar 21 '12 at 09:29

Andrey Gurinov

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Thanks for the edit Andrey - appreciate it. It seems crazy to have to cast this as an object though (to me anyway). – SkonJeet Mar 21 '12 at 09:56

score 8 · Answer 2 · answered Mar 21 '12 at 09:24

8

Try DBNull.Value

if (!string.IsNullOrEmpty(activity.StaffId))
   param.Value = activity.StaffId;
else
  param.Value=DBNull.Value;

answered Mar 21 '12 at 09:24

KV Prajapati

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is there a way of using the ? operator for a sort of shorthand if else statement here?? It seems to not like the String/DBNull.Value conversion!? – SkonJeet Mar 21 '12 at 09:33
1

Try this: param.Value = !string.IsNullOrEmpty(activity.StaffId) ? activity.StaffId : (object)DBNull.Value; – Andrey Gurinov Mar 21 '12 at 09:41

score 4 · Answer 3 · answered Apr 05 '18 at 18:28

4

You can always use the null-coalescing operator (??)

param.Value = activity.StaffId ?? (object)DBNull.Value;

answered Apr 05 '18 at 18:28

Niko Yakimov

73
4

score 3 · Answer 4 · answered Mar 21 '12 at 09:25

3

You could use DBNull.Value:

param.Value = DBNull.Value;

answered Mar 21 '12 at 09:25

Andomar

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Inserting NULL to SQL DB from C# DbCommand

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