/// <summary>
/// 获取数据表中某列的值的个数（不重复）
/// </summary>
/// <param name="dt"></param>
/// <param name="fieldName"></param>
/// <returns></returns>
public static int GetColDistinctCount(this MDataTable dt, string fieldName)
{
var arr = dt.GetColDistinct(fieldName);
return(arr.Length);
}
