Generate Auto ID With Prefix

There are several way to generate auto id. Here is a method for generating auto ID from program. By providing prefix, data table with/without data and column name from program, it will return a new ID with prefix. For example...
First we need to fill a data table by selecting an sql table. Then call this method by passing the parameters ---
getNewIdWithPrefix("CUS-", dataTable, "customerID");
It will return 'CUS-00001'

--------------ID Generating Method---------------
public static string getNewIdWithPrefix(string prefix, DataTable dt, string columnName)
    {
        string newId = string.Empty;
        int maxId = 0;

        if (dt.Rows.Count > 0)
        {
            DataTable idTable = new DataTable();
            idTable.Columns.Add("id", typeof(int));
            foreach (DataRow dtRow in dt.Rows)
            {
                DataRow dr = idTable.NewRow();
                if (dtRow[columnName].ToString().Contains(prefix))
                {
                    dr["id"] = int.Parse(dtRow[columnName].ToString().Substring(prefix.Length));
                    idTable.Rows.Add(dr);
                }
                else
                {
                    dr["id"] = 0;
                    idTable.Rows.Add(dr);
                }
            }
            maxId = (int)idTable.Compute("MAX(id)", "") + 1;
        }
        else
        {
            maxId = 1;
        }
            
        newId = prefix + maxId.ToString("#00000");

        return newId;
    }