如何清除以下情况例外,当我运行下面的命令在C#
DropDownList7有卡,打印机等
{C}
:7909353 |会员 SqlCommand cmd = new SqlCommand("SELECT ItemName FROM ItemMaster where CategoryID=(SELECT CateoryID FROM Category where CategoryName= \"" + DropDownList7.SelectedItem.Text + "\" ) ", con);