从一个不在另一个表中的表中检索数据

Question

sq = "select roomno,blockname from roommanage where roomno not in( select *from availableroom)";
ds = dc.filldata(sq);
GridView1.DataSource = ds.Tables["t1"];
GridView1.DataBind();

有一个错误：

Only one expression can be specified in the select list when the subquery is not introduced with EXIST。

我该如何解决这个问题？

Answer 1

在你的“不在”中应该只返回1列。请尝试以下代码。

sq = "select roomno,blockname from roommanage where roomno not in( select id from availableroom)";
    ds = dc.filldata(sq);
    GridView1.DataSource = ds.Tables["t1"];
    GridView1.DataBind();

Answer 2

两列试试这个

    sq = "SELECT roomno,blockname FROM roommanage 
WHERE roomno NOT IN( SELECT id FROM availableroom) 
AND blockname NOT IN(SELECT yourcolumn FROM blockname)";
ds = dc.filldata(sq);
GridView1.DataSource = ds.Tables["t1"];
GridView1.DataBind();