IFNULL error in C# with MySql

"Message: FUNCTION <databasename>.IFNULL does not exist"

command.CommandText = "select IFNULL(SL_NO,0) SL_NO, IFNULL(STUD_CODE,'') STUD_CODE, IFNULL(STUD_NAME,'') STUD_NAME from STUDENTREGISTER";

public List GetStudentCodeInGrid(string StudCode)
        {
            List studDetailsList = new List();
            MySqlConnection connection = new MySqlConnection(connectionString);
            connection.Open();

            MySqlCommand command = new MySqlCommand();
            command.CommandText = "select COALESCE(SL_NO) SL_NO, COALESCE(STUD_CODE,'')STUD_CODE, COALESCE(STUD_NAME,'') STUD_NAME from STUD_CODE WHERE STUDENTREGISTER LIKE '" + studCode + "%' ORDER BY STUD_CODE";
            command.Connection = connection;

            MySqlDataReader reader = command.ExecuteReader();

            while (reader.Read())
            {
                StudDetails studDetails = new StudDetails();

                studDetails.SNO = Convert.ToInt32(reader["SL_NO"]);
                studDetails.StudCode = reader["STUD_CODE"].ToString();
                studDetails.StudName = reader["STUD_NAME"].ToString();

                studDetailsList.Add(studDetails);
            }

            return studDetailsList;
        }