Delete Commad with Null Parameter Value

Sometimes we need to make where conditions with null value.
If we use Command Paramenters the first thing we make is:

      
       SqlCommand.CommandText = "DELETE table WHERE field1 = @param1";

       SqlCommand.Parameters.Add(new SqlParameter("@param1", DBNull.Value)

Your problem is that you cannot use the '=' operator in SQL for null value.  
Instead, you need to generate different SQL for this case.
See the following example:

---

public void DeleteYourRecord(SqlConnection con, string param1, string param2, string param3)

        {

            SqlCommand com = new SqlCommand();

            com.Connection = con;

            com.Connection = con;

            com.CommandText = "DELETE table" +

                              "WHERE field1 = @param1 AND field2 = @param2 ";

            com.Parameters.Add(new SqlParameter("@param1", param1));

            com.Parameters.Add(new SqlParameter("@param2", param2));

            if (param3.Trim() == "")

            {

                com.CommandText += " AND field3 is null";

            }

            else

            {

                com.CommandText += " AND field3 = @param3";

                com.Parameters.Add(new SqlParameter("@param3", param3));

            }

            com.ExecuteNonQuery();

        }




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