在下面的例子中實現了3個Join方法，其目的是把兩個DataTable連接起來，相當於SQL（SQL Server培訓 MySQL培訓 ）的Inner Join方法，返回DataTable的所有列。
如果兩個DataTable中的DataColumn有重復的話，把第二個設置為ColumnName "_Second",下面是代碼，希望對大家有所幫助。
using System;
using System.Data;
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namespace WindowsApplication1
{
public class SQLOps
{
public SQLOps()
{
}
public static DataTable Join (DataTable First, DataTable Second, DataColumn[] FJC, DataColumn[] SJC)
{
//創建一個新的DataTable
DataTable table = new DataTable("Join");
// Use a DataSet to leverage DataRelation http://www.mscto.com
using(DataSet ds = new DataSet())
{ http://www.mscto.com
//把DataTable Copy到DataSet中
ds.Tables.AddRange(new DataTable[]{First.Copy(),Second.Copy()});
DataColumn[] parentcolumns = new DataColumn[FJC.Length];
for(int i = 0; i < parentcolumns.Length; i )
{
parentcolumns[i] = ds.Tables[0].Columns[FJC[i].ColumnName];
}
DataColumn[] childcolumns = new DataColumn[SJC.Length];
for(int i = 0; i < childcolumns.Length; i )
{
childcolumns[i] = ds.Tables.Columns[SJC[i].ColumnName];
}
//創建關聯
DataRelation r = new DataRelation(string.Empty,parentcolumns,childcolumns,false);
ds.Relations.Add(r);
//為關聯表創建列
for(int i = 0; i < First.Columns.Count; i )
{
table.Columns.Add(First.Columns[i].ColumnName, First.Columns[i].DataType);
}
for(int i = 0; i < Second.Columns.Count; i )
{
//看看有沒有重復的列，如果有在第二個DataTable的Column的列明後加_Second
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if(!table.Columns.Contains(Second.Columns[i].ColumnName))
table.Columns.Add(Second.Columns[i].ColumnName, Second.Columns[i].DataType);
else
table.Columns.Add(Second.Columns[i].ColumnName "_Second", Second.Columns[i].DataType);
}
table.BeginLoadData();
foreach(DataRow firstrow in ds.Tables[0].Rows) http://www.mscto.com
{
//得到行的數據
DataRow[] childrows = firstrow.GetChildRows(r);
if(childrows != null && childrows.Length > 0)
{
object[] parentarray = firstrow.ItemArray;
foreach(DataRow secondrow in childrows)
{
object[] secondarray = secondrow.ItemArray;
object[] joinarray = new object[parentarray.Length secondarray.Length];
Array.Copy(parentarray,0,joinarray,0,parentarray.Length);
Array.Copy(secondarray,0,joinarray,parentarray.Length,secondarray.Length);
table.LoadDataRow(joinarray,true);
}
}
}
table.EndLoadData();
}
return table;
}
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public static DataTable Join (DataTable First, DataTable Second, DataColumn FJC, DataColumn SJC)
{
return Join(First, Second, new DataColumn[]{FJC}, new DataColumn[]{SJC});
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}
public static DataTable Join (DataTable First, DataTable Second, string FJC, string SJC)
{
return Join(First, Second, new DataColumn[]{First.Columns[FJC]}, new DataColumn[]{First.Columns[SJC]});
}
}
}
