○作者:浪漫十一狼 在下面的例子中实现了3...... 作者:浪漫十一狼 在下面的例子中实现了3个Join方法,其目的是把两个DataTable连接起来,相当于Sql的Inner Join方法,返回DataTable的所有列。 如果两个DataTable中的DataColumn有重复的话,把第二个设置为ColumnName+"_Second",下面是代码,希望对大家有所帮助。 using System; using System.Data; namespace WindowsApplication1 { public class SQLOps { public SQLOps() { } public static DataTable Join (DataTable First, DataTable Second, DataColumn[] FJC, DataColumn[] SJC) { //创建一个新的DataTable DataTable table = new DataTable("Join"); // Use a DataSet to leverage DataRelation using(DataSet ds = new DataSet()) { //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[1].Columns[SJC[i].ColumnName]; } //创建关联 DataRelation r = new DataRelation(string.Empty,parentcolumns,childcolumns,false); ds.Relations.Add(r); //为关联表创建列 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++) { //看看有没有重复的列,如果有在第二个DataTable的Column的列明后加_Second 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) { //得到行的数据 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; } public static DataTable Join (DataTable First, DataTable Second, DataColumn FJC, DataColumn SJC) { return Join(First, Second, new DataColumn[]{FJC}, new DataColumn[]{SJC}); } 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]}); } } } |
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