C#中去掉表中重复的数据
/// <summary>
/// 去掉表中重复的数据 int
/// </summary>
/// <param name="SourceTable">原始表</param>
/// <param name="FieldName">重复的字段</param>
/// <returns></returns>
public DataTable SelectDistinct(DataTable SourceTable, string FieldName)
{
DataTable dt = new DataTable();
for (Int32 i = 0; i < SourceTable.Columns.Count; i++)
{
string fieldName=SourceTable.Columns[i].Caption;
dt.Columns.Add(fieldName, SourceTable.Columns[fieldName].DataType);
}
DataRow dataRow = dt.NewRow();
foreach (DataRow dr in SourceTable.Select("", FieldName))
{
string str=dr[FieldName].ToString();
if(str != string.Empty)
{
if(int.Parse(str)!=0)
{
if (dataRow == null || !(ColumnEqual(dataRow[FieldName], dr[FieldName])))
{
dataRow=dr;
DataRow row = dt.NewRow();
for (int i = 0; i < dataRow.ItemArray.Length; i++)
{
row[i] = dataRow[i];
}
dt.Rows.Add(row);
}
}
}
}
return dt;
}
/// <summary>
/// 去掉表中重复的数据 字段 string
/// </summary>
/// <param name="SourceTable">原始表</param>
/// <param name="FieldName">重复的字段</param>
/// <returns></returns>
public DataTable SelectDistinctStr(DataTable SourceTable, string FieldName)
{
DataTable dt = new DataTable();
for (Int32 i = 0; i < SourceTable.Columns.Count; i++)
{
string fieldName=SourceTable.Columns[i].Caption;
dt.Columns.Add(fieldName, SourceTable.Columns[fieldName].DataType);
}
DataRow dataRow = dt.NewRow();
foreach (DataRow dr in SourceTable.Select("", FieldName))
{
string str=dr[FieldName].ToString();
if(str != string.Empty)
{
if (dataRow == null || !(ColumnEqual(dataRow[FieldName], dr[FieldName])))
{
dataRow=dr;
DataRow row = dt.NewRow();
for (int i = 0; i < dataRow.ItemArray.Length; i++)
{
row[i] = dataRow[i];
}
dt.Rows.Add(row);
}
}
}
return dt;
}
private bool ColumnEqual(object A, object B)
{
if(A == DBNull.Value && B == DBNull.Value) // 两个都是 DBNull.Value
return true;
if(A == DBNull.Value || B == DBNull.Value) // 只有一个是 DBNull.Value
return false;
return (A.Equals(B));// 正常比较
}
/// <summary>
/// 表中筛选数据
/// </summary>
/// <param name="SourceTable">原始表</param>
/// <param name="FieldName1">表里的字段名</param>
/// <param name="FieldName2">筛选的数据</param>
/// <returns></returns>
public DataTable SelectByField(DataTable SourceTable,string FieldName1, string FieldName2)
{
DataTable dt = new DataTable();
for (Int32 i = 0; i < SourceTable.Columns.Count; i++)
{
string fieldName=SourceTable.Columns[i].Caption;
dt.Columns.Add(fieldName, SourceTable.Columns[fieldName].DataType);
}
foreach (DataRow dr in SourceTable.Select(" "+FieldName1+" = '" + FieldName2 + "'"))
{
DataRow row = dt.NewRow();
for (int i = 0; i < dr.ItemArray.Length; i++)
{
row[i] = dr[i];
}
dt.Rows.Add(row);
}
return dt;
}
