SQL 3表连接IS NOT NULL

Question

我有3个表com_co，sim，clist

$list = "SELECT com_co.*, sim.*, clist.*
         FROM  com_co
            INNER   JOIN sim
              ON sim.id = com_co.component_id
            INNER   JOIN clist
              ON com_co.complex_id = clist.id AND IS NOT NULL
         WHERE comp_c_code = '$rowId'";

如果我删除第二个INNER JOIN，但我无法从clist获取数据，则会运行查询。表complex_id中的列com_co可以是null。如果它是not null并且有一个值（来自id的{​​{1}}），我希望能够从clist获取clist的数据。

如果我运行此查询，则不会返回任何数据。

Answer 1

试试这个

$list = "SELECT com_co.*, sim.*, clist.*
     FROM  com_co
        INNER   JOIN sim
          ON sim.id = com_co.component_id
        INNER   JOIN clist
          ON com_co.complex_id = clist.id 
     WHERE comp_c_code = '$rowId' AND com_co.complex_id  IS NOT NULL";