[LINQ] 查詢DataRow欄位(LINQ to DataSet)

2010-09-22

23551
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LINQ
2010-09-23

除了用DataView來查詢DataRow之外，我們還可以用LINQ查詢DataRow，這真是一個簡單的方法，不禁越來越喜歡LINQ。

首先我們建立一個DataTable

DataTable table = new DataTable("newTable");
string[] field = new string[] { "ID", "Name", "Phone" };
foreach (var item in field)
{
    DataColumn column = new DataColumn();
    column.ColumnName = item;
    column.Caption = item;
    column.AllowDBNull = true;
    table.Columns.Add(column);
}
DataRow row = table.NewRow();
row["ID"] = "1";
row["Name"] = "王大明";
row["Phone"] = "0780";
table.Rows.Add(row);
row = table.NewRow();
row["ID"] = "2";
row["Name"] = "余小章";
row["Phone"] = "0781";
table.Rows.Add(row);
this._Table = table;
dataGridView1.DataSource = table;

再來建立LINQ查詢方法

public void QueryLINQ(){
    //查尋DataTable的欄位
    var query = from contact in this._Table.AsEnumerable()
                where contact.Field<string>("Name").IndexOf("余") > -1//過濾條件
                select contact;
    //將查詢結果轉成DataTable
    DataTable table = query.CopyToDataTable();
    dataGridView2.DataSource = table;
}

順道把DataView的查詢方法列出來

public void QueryView(){
    DataView view = new DataView(this._Table);
    view.RowFilter = "Name='" + "余小章" + "'";
    DataTable table = view.ToTable();
    dataGridView3.DataSource = table;
}

執行結果是一樣的