public FilterCondition(TableField tf, List<string> valueList)
     : base(tf.Table, tf.Field)
 {
     if (valueList==null)
         throw new ArgumentNullException("valueList", "Do not input any value for FilterCondition");
     values=valueList;
 }
 public FilterCondition(TableField tf, params string[] valueList)
     :base(tf.Table,tf.Field)
 {
     if (valueList.Length<=0)
         throw new ArgumentNullException("valueList","Do not input any value for FilterCondition");
     if (values == null)
         values = new List<string>();
     values.Clear();
     values.AddRange(valueList);
 }