Question

I have a stored procedure parameter as:

@ScmDate DateTime = NULL

From C# when I pass the parameter as below, it gives error: Error converting nvarchar to datetime.

if (txtWaitedDate.Text != "")
    cmdTwMainEntry.Parameters.AddWithValue("@scmDate", Convert.ToDateTime(txtWaitedDate.Text));

Even though I have given default value of this parameter as NULL, but when the above C# condition is not fulfilled, it gives error.

Edited:

I get error only when I leave TextBox empty.

Answer 1

I suspect your date format is not what is expected by sql server, try to convert it with DateTime.TryParse and the right format provider for your SQL Server instance .

This error can happen for example when one is using mm/dd/yyyy format and the other is using dd/mm/yyyy.

EDIT

Changing the parameter type by hand should work anyway.
Try with this code, should work :

    SqlParameter parameter = cmdTwMainEntry.Parameters.Add("@scmDate", System.Data.SqlDbType.DateTime);
        // Set the value.
        parameter.Value = (!string.IsNullOrEmpty(txtWaitedDate.Text)) ? Convert.ToDateTime(txtWaitedDate.Text) : System.DbNull.Value;