我正在尝试使用CriteriaQuery编写一个SQL查询，但是这样做很难。该查询基本上获得了装运清单，并按其授权日期对其进行了排序。此授权日期表示为状态转换消息表中第一条记录的日期属性，初始状态为3，最终状态为4。这是我的查询：
SELECT s.id
FROM shipment s
ORDER BY (SELECT min(stm.date)
FROM status_transition_message stm
WHERE stm.initial_status = 1 AND stm.final_status = 3 AND stm.shipment_id = s.id) desc;
我尝试了多种不同的解决方案，但到目前为止都没有奏效。
我当前的迭代如下：
private void sortByAuthDate(Root<ShipmentTbl> root, CriteriaQuery<?> query, CriteriaBuilder builder, ListSort sort) {
Subquery<Timestamp> authDateQuery = query.subquery(Timestamp.class);
Root<StatusTransitionMessageTbl> stmRoot = authDateQuery.from(StatusTransitionMessageTbl.class);
Predicate shipmentId = builder.equal(stmRoot.<ShipmentTbl>get("shipment").<String>get("id"), root.<String>get("id"));
Predicate initialStatus = builder.equal(stmRoot.<Integer>get("initialStatus"), 3);
Predicate finalStatus = builder.equal(stmRoot.<Integer>get("finalStatus"), 4);
// returns the authorization date for each queried shipment
authDateQuery.select(builder.least(stmRoot.<Timestamp>get("date")))
.where(builder.and(shipmentId, initialStatus, finalStatus));
Expression<Timestamp> authDate = authDateQuery.getSelection();
Order o = sort.getSortDirection() == ListSort.SortDirection.ASC ? builder.asc(authDate) : builder.desc(authDate);
query.multiselect(authDate).orderBy(o);
}
此解决方案的问题在于，由CriteriaQuery生成的JPQL查询不支持ORDER BY子句中的子查询，从而导致解析异常。
答案 0 :(得分：1)
我的CriteriaQuery-fu不足以帮助您完成那部分工作，但是您可以将SQL查询重写为此：
SELECT s.id
FROM shipment s
LEFT JOIN status_transition_message stm
ON stm.initial_status = 1 AND stm.final_status = 3 AND stm.shipment_id = s.id
GROUP BY s.id
ORDER BY min(stm.date) DESC;
对我来说，这似乎比在ORDER BY子句中运行相关子查询要快得多，特别是在优化器欠佳的RDBMS上。
答案 1 :(得分：0)
所以我尝试遵循@Lukas Eder解决方案并达到以下解决方案：
private void sortByAuthDate(Root<ShipmentTbl> root, CriteriaQuery<?> query, CriteriaBuilder builder, ShipmentListSort sort) {
Join<ShipmentTbl, StatusTransitionMessageTbl> shipmentStatuses = root.join("shipmentStatus", JoinType.LEFT);
Predicate initialStatus = builder.equal(shipmentStatuses.<Integer>get("initialStatus"), 1);
Predicate finalStatus = builder.equal(shipmentStatuses.<Integer>get("finalStatus"), 3);
Expression<Timestamp> authDate = builder.least(shipmentStatuses.<Timestamp>get("date"));
Order o = sort.getSortDirection() == ShipmentListSort.SortDirection.ASC ? builder.asc(authDate) : builder.desc(authDate);
shipmentStatuses.on(builder.and(initialStatus, finalStatus));
query.multiselect(authDate).groupBy(root.<String>get("id")).orderBy(o);
}
}
但是现在它抛出了这个异常：
ERROR o.h.e.jdbc.spi.SqlExceptionHelper - ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list
之所以发生这种情况，是因为该查询稍后只会得到不同的货件，并且要求在选择中也显示排序列。问题是我不知道如何强制CriteriaQuery将该列保留在SELECT语句中。它只会自动放入ORDER BY。
这是在我的测试中正在执行的JPQL查询：
select
distinct generatedAlias0
from
ShipmentTbl as generatedAlias0
left join
generatedAlias0.shipmentStatus as generatedAlias1 with ( generatedAlias1.initialStatus=:param0 )
and (
generatedAlias1.finalStatus=:param1
)
where
lower(generatedAlias0.shipmentName) like :param2
group by
generatedAlias0.id
order by
min(generatedAlias1.date) desc
和生成的SQL查询：
select
distinct shipmenttb0_.id as id1_13_,
shipmenttb0_.archived_date as archived2_13_,
shipmenttb0_.auth_code as auth_cod3_13_,
shipmenttb0_.authorization_date as authoriz4_13_,
shipmenttb0_.booked_in_by_user as booked_i5_13_,
shipmenttb0_.business_channel as business6_13_,
shipmenttb0_.courier as courier7_13_,
shipmenttb0_.courier_amount as courier_8_13_,
shipmenttb0_.courier_currency as courier_9_13_,
shipmenttb0_.ship_to as ship_to39_13_,
shipmenttb0_.estimated_shipment_date as estimat10_13_,
shipmenttb0_.last_updated_date as last_up11_13_,
shipmenttb0_.measurement_unit as measure12_13_,
shipmenttb0_.original_submitted_date as origina13_13_,
shipmenttb0_.packaging_type as packagi14_13_,
shipmenttb0_.placeholder_message as placeho15_13_,
shipmenttb0_.scheduled_period_of_day as schedul16_13_,
shipmenttb0_.scheduled_shipment_date as schedul17_13_,
shipmenttb0_.ship_from as ship_fr40_13_,
shipmenttb0_.ship_origin as ship_or41_13_,
shipmenttb0_.shipment_name as shipmen18_13_,
shipmenttb0_.status as status19_13_,
shipmenttb0_.submitted_date as submitt20_13_,
shipmenttb0_.supplier_contact_email as supplie21_13_,
shipmenttb0_.supplier_contact_name as supplie22_13_,
shipmenttb0_.supplier_contact_phone_number as supplie23_13_,
shipmenttb0_.supplier_email as supplie24_13_,
shipmenttb0_.supplier_secondary_contact_email as supplie25_13_,
shipmenttb0_.supplier_secondary_contact_name as supplie26_13_,
shipmenttb0_.supplier_secondary_contact_phone_number as supplie27_13_,
shipmenttb0_.tenant as tenant28_13_,
shipmenttb0_.total_received_boxes as total_r29_13_,
shipmenttb0_.total_units as total_u30_13_,
shipmenttb0_.total_value as total_v31_13_,
shipmenttb0_.total_volume as total_v32_13_,
shipmenttb0_.total_weight as total_w33_13_,
shipmenttb0_.tracking_number as trackin34_13_,
shipmenttb0_.tt_note as tt_note35_13_,
shipmenttb0_.tt_priority as tt_prio36_13_,
shipmenttb0_.updated_by_user as updated37_13_,
shipmenttb0_.weight_unit as weight_38_13_
from
shipment shipmenttb0_
left outer join
status_transition_message shipmentst1_
on shipmenttb0_.id=shipmentst1_.shipment_id
and (
shipmentst1_.initial_status=?
and shipmentst1_.final_status=?
)
where
lower(shipmenttb0_.shipment_name) like ?
group by
shipmenttb0_.id
order by
min(shipmentst1_.date) desc limit ?