通过 is null 或 is not null 可以来判断空字段。
is null
is not null
空字段筛选过程演示: select image_src, pk_group from sm_appmenuitem where image_src is null;
select image_src, pk_group from sm_appmenuitem where image_src is null;
非空字段筛选过程演示: select image_src, pk_group from sm_appmenuitem where image_src is not null;
select image_src, pk_group from sm_appmenuitem where image_src is not null;