我对 JPA 标准有疑问。
这是我的 JPA 条件查询：
CriteriaBuilder criteriaBuilder = getEm().getCriteriaBuilder();
CriteriaQuery<InventoryItemSumReport> query = criteriaBuilder.createQuery(InventoryItemSumReport.class);
Root<InventoryItemDetail> from = query.from(InventoryItemDetail.class);
Join<InventoryItemDetail, InventoryItem> joinItem = from.join(InventoryItemDetail_.inventoryItem);
Predicate where = criteriaBuilder.lessThanOrEqualTo(from.get(InventoryItemDetail_.effectiveDate), date);
query.multiselect(joinItem.get(InventoryItem_.product),joinItem.get(InventoryItem_.facility),joinItem.get(InventoryItem_.customer));
query.groupBy(joinItem.get(InventoryItem_.product),joinItem.get(InventoryItem_.facility),joinItem.get(InventoryItem_.customer));
query.where(where);
TypedQuery<InventoryItemSumReport> createQuery = getEm().createQuery(query);
List<InventoryItemSumReport> resultList = createQuery.getResultList();
以下是 JPA 提供程序生成的查询结果：
select
inventoryi1_.PRODUCT_ID as col_0_0_,
inventoryi1_.FACILITY_ID as col_1_0_,
inventoryi1_.CUSTOMER_ID as col_2_0_
from
INVENTORY_ITEM_DETAIL inventoryi0_
inner join
INVENTORY_ITEM inventoryi1_
on inventoryi0_.INVENTORY_ITEM_ID=inventoryi1_.ID
inner join
PRODUCT product2_
on inventoryi1_.PRODUCT_ID=product2_.ID
inner join
FACILITY facility3_
on inventoryi1_.FACILITY_ID=facility3_.ID
inner join
CUSTOMER customer4_
on inventoryi1_.CUSTOMER_ID=customer4_.ID
where
inventoryi0_.EFFECTIVE_DATE<= ?
group by
inventoryi1_.PRODUCT_ID ,
inventoryi1_.FACILITY_ID ,
inventoryi1_.CUSTOMER_ID
但我想要以下查询：
select
inventoryi1_.PRODUCT_ID as col_0_0_,
inventoryi1_.FACILITY_ID as col_1_0_,
inventoryi1_.CUSTOMER_ID as col_2_0_
from
INVENTORY_ITEM_DETAIL inventoryi0_
inner join
INVENTORY_ITEM inventoryi1_
on inventoryi0_.INVENTORY_ITEM_ID=inventoryi1_.ID
inner join
PRODUCT product2_
on inventoryi1_.PRODUCT_ID=product2_.ID
inner join
FACILITY facility3_
on inventoryi1_.FACILITY_ID=facility3_.ID
left join
CUSTOMER customer4_
on inventoryi1_.CUSTOMER_ID=customer4_.ID
where
inventoryi0_.EFFECTIVE_DATE<= ?
group by
inventoryi1_.PRODUCT_ID ,
inventoryi1_.FACILITY_ID ,
inventoryi1_.CUSTOMER_ID
使用左连接 CUSTOMER来获得Customers空值的结果。
Customer, Product,Facility都是实体，InventoryItemSumReport而是 Value 对象或 DTO。
public class InventoryItemSumReport implements Serializable {
private static final long serialVersionUID = 1L;
private Product product;
private Facility facility;
private Customer customer;
public InventoryItemSumReport(Product product, Facility facility, Customer customer) {
super();
this.product = product;
this.facility = facility;
this.customer = customer;
}
}