update null for type date

Question

I have a sentence follow:

    string strSQL = "update pl_poli set ag_vouch = ' ',ag_vdate = #, ag_vmode = null where
 pl_no = '" + textBox5.Text + "' and pl_endtno ='" + textBox6.Text + "'";

I can't update because error "data type mismath". i have fill ag_vdate is type date I want to Update it -> null Please can you help me. Thank you so much.

Answer 1

In your case you cannot pass " # " at datetime column because sql server consider this as varchar value and not able to convert this in datetime so...

Try to do as below

using (SqlConnection connection = new SqlConnection(connectionString))
using (SqlCommand command = connection.CreateCommand())
{
    command.CommandText = "INSERT INTO table1 (column1, column2) VALUES (@param1, @param2)";

    command.Parameters.Add("@param1", SqlDbType.DateTime).Value = 
        DateTime.TryParse(txtDate.Text, out d) ?
            (object)d :
            DBNull.Value // inserting NULL
    ...

    connection.Open();
    command.ExecuteNonQuery();
}