爲什麼第一個聲明不返回第二個數字?聲明未返回正確的數字或行
select random_selection.randnum,
random_selection.createddate,
random_selection.ozip3,
random_selection.boxid,
random_selection.boxaddr,
random_selection.locdesc,
random_selection.loccity,
random_selection.lastmf,
random_selection.lastsat,
random_selection.boxtype,
random_selection.svcclas,
random_selection.dropzip5,
dropper_city_brk_2.dropper_id
from random_selection, dropper_city_brk_2
where random_selection.ozip3 = dropper_city_brk_2.zip3
and dropper_city_brk_2.dropper_id <> 10002
and random_selection.dropper_id is null
order by dropper_id;
其次聲明:
select count(*) from random_selection where dropper_id is null;
嗯,技術上,_might_不是一樣的 – Gerrat
正確的,他們可能不一樣。但是你有一個查詢加入一個表,第二個查詢不是。這是一個很大的區別。 – Taryn
第二個查詢應返回第一個查詢中的一個或多個行,我要的是將dropper_city_brk_2.dropper_id添加到結果中,其中random_selection.ozip3 = dropper_city_brk_2.zip3 – Mike