什麼是語法

Question

我試圖運行此代碼，但我得到了不止一行（這是我想要的），但顯然：=運算符只能處理一個值。什麼我需要獲得多行回（一列），這樣我可以推入下一個select語句

set @oids :=(

    SELECT OBJECT_ID 
    FROM aaa K 
    WHERE K.TYPE IN ('ISSN', 'ISBN') 
    GROUP BY K.OBJECT_ID 
    HAVING count(distinct K.TYPE) = 2 

); 

select * 
from aaa 
where OBJECT_ID in (@oids); 

Answer 1

只需使用一個單一的查詢沒有變量

select * 
from aaa 
where OBJECT_ID in (SELECT OBJECT_ID 
        FROM aaa K 
        WHERE K.`TYPE` IN ('ISSN', 'ISBN') 
        GROUP BY K.OBJECT_ID 
        HAVING count(distinct K.TYPE) = 2 
        );