[英]Sub-Select In hibernate criteria
我有一個帶有列名的sql表A.
name, id1, id2, val1
和一個帶有列名的表B.
id1, id2, key1, key2
這是我的SQL查詢
SELECT
v1.id1,
v1.id2
FROM (
SELECT
A.id1,
A.id2,
min(val1) AS x
FROM A
JOIN B ON A.id1 = B.id1 AND A.id2 = B.id2
GROUP BY A.id1, A.id2
) AS v1
WHERE v1.x > 10
使用DetachedCriteria我能夠形成子查詢
DetachedCriteria subCriteria = DetachedCriteria.forClass(A_model.class);
subCriteria.createAlias("b", "b_model");
subCriteria.setProjection(Projections.projectionList()
.add(Projections.groupProperty("id1"))
.add(Projections.groupProperty("id2"))
.add(Projections.min("val1"),"x");
但我在創建外部查詢時遇到了困難。
任何建議我如何創建上述SQL的標准?
謝謝你的期待。
暫時不支持from
子句中的子選擇。 但是,通過使用HAVING
子句,可以以更簡單,更高效的形式重寫您的查詢:
SELECT A.id1, A.id2,
FROM A JOIN B ON A.id1 = B.id1 AND A.id2 = B.id2
GROUP BY A.id1, A.id2
HAVING min(val1) > 10
上述查詢可以輕松移植到HQL或Criteria。
考慮為您需要的數據創建視圖:
create view A_B_BY_ID1_AND_ID2 as
select A.id1,
A.id2,
min( val1 ) as x
from A
join B on A.id1 = B.id1 and A.id2 = B.id2
group by A.id1,
A.id2
然后創建一個DTO來表示這些數據:
@Entity(table="A_B_BY_ID1_AND_ID2")
@Data //are you on board with lombok?
public class ABById1AndId2 {
@Column
private int x;
@Column
private int id1;
@Column
private int id2;
}
然后像其他任何東西一樣訪問:
session.createCriteria(ABById1AndId2.class).add(Restrictions.gt("x", 10)).list();
HQL和Criteria對象既不支持從Select中選擇。 這里的解決方案是命名查詢。
@NamedNativeQueries({
@NamedNativeQuery(
name = "findV1",
query = "SELECT
v1.id1,
v1.id2
FROM (
SELECT
A.id1,
A.id2,
min(val1) AS x
FROM A
JOIN B ON A.id1 = B.id1 AND A.id2 = B.id2
GROUP BY A.id1, A.id2
) AS v1
WHERE v1.x > 10"
)
})
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