过滤DataTable中的指定字段重复的行

#region 过滤DataTable中的指定字段重复的行


/// <summary>
/// 过滤DataTable中的指定字段重复的行
/// </summary>
/// <param name= "dt "> </param>
/// <param name= "FieldName "> </param>
/// <returns> </returns>
public DataTable SelectDistinctByField(DataTable dt, string FieldName)
{
DataTable returnDt = new DataTable();
returnDt = dt.Copy();//将原DataTable复制一个新的
DataRow[] drs = returnDt.Select(" ", FieldName);//将DataTable按指定的字段排序
object LastValue = null;
for (int i = 0; i < drs.Length; i++)
{
if ((LastValue == null) || (!(ColumnEqual(LastValue, drs[i][FieldName]))))
{
LastValue = drs[i][FieldName];
continue;
}


drs[i].Delete();
}


return returnDt;
}


private bool ColumnEqual(object A, object B)
{
// Compares two values to see if they are equal. Also compares DBNULL.Value.
// Note: If your DataTable contains object fields, then you must extend this
// function to handle them in a meaningful way if you intend to group on them.


if (A == DBNull.Value && B == DBNull.Value) // both are DBNull.Value
return true;
if (A == DBNull.Value || B == DBNull.Value) // only one is DBNull.Value
return false;
return (A.Equals(B)); // value type standard comparison
}


#endregion