查找MySQL的複製與行JPA QueryDSL

Question

我想在QueryDSL JPA

SELECT authorizationitem.* 
FROM authorizationitem 
INNER JOIN 
(
    SELECT `authorize` 
    FROM authorizationitem 
    GROUP BY `authorize` 
    HAVING COUNT(*)>1 
) a2 
    ON authorizationitem.`authorize` = a2.`authorize`; 

爲了執行這個SQL請求，查找重複行的表，我應該執行此請求。但是對於QueryDSL，我找不到寫這個的方法。

它似乎QueryDSL不允許子查詢內部聯接：■

什麼建議嗎？

感謝 問候，

Answer 1

您可以嘗試在WHERE子句中使用子查詢，但它可能會比在子查詢FROM子句效率較低。確保在authorizationitem.authorize上有一個索引來優化連接和GROUP BY。

SELECT authorizationitem.* 
FROM authorizationitem 
WHERE EXISTS (
    SELECT `authorize` 
    FROM authorizationitem2 
    WHERE authorizationitem2.authorize = authorizationitem.authorize 
    GROUP BY `authorize` 
    HAVING COUNT(*)>1 
); 

或

SELECT authorizationitem.* 
FROM authorizationitem 
WHERE (
    SELECT count(*) 
    FROM authorizationitem2 
    WHERE authorizationitem2.authorize = authorizationitem.authorize 
    GROUP BY `authorize` 
) > 1; 

Answer 2

你不能用HQL/JPQL表達這一點，所以你需要使用SQL來Expess同時此。 Querydsl JPA提供了通過API來表達JPQL和SQL查詢的可能性。