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;

}