嵌套SQL查询在C＃中:如何设置在C＃中查询。
("SELECT * FROM Purchase where ItemID=' + SELECT ItemID FROM ItemMaster where ItemName='" + DropDownList3.SelectedItem.Text + '"'" and CategoryID='" + SELECT CategoryID FROM ItemMaster where ItemName=' "+ DropDownList3.SelectedItem.Text + '"' ", con);