SelectCommand="SELECT * FROM [Student] WHERE ([ClassID] = SELECT [ClassID] FROM [Student] WHERE ([username] = @username)">
<SelectParameters>
<asp:SessionParameter Name="username" SessionField="username1" Type="String" />
</SelectParameters>
</asp:SqlDataSource>
我想查询用户所在的班级的所有学生信息
username1是session值，作为参数查询出CLASSID，再把CLASSID作为参数查询学生信息。请问语法怎么改？