MySQL 到 JPQL 内部联接

Question

我是 JPQL 的新手，在将我的 SQL 翻译成 JPQL 时遇到了一些困难。我有一个适用于 MYSQL:

的简单查询

SELECT askorder.price, bidorder.price from OrderBook JOIN askorder 
ON OrderBook.ASKORDERID_ORDERID = askorder.ORDERID
JOIN bidorder ON OrderBook.BIDORDERID_ORDERID = bidorder.ORDERID
WHERE askorder.ORDERID = 2;

我试图将其翻译成 JPQL，但我确信它是错误的。具体来说，我认为它可能是 ON 关键字，我不确定如何将其转换为 JPQL：

@NamedQuery(
    name="findOrderBooksPrices",
    query="SELECT ao.price, bo.price from OrderBook bo, OrderBook ao" +
    "INNER JOIN ao ON bo.ASKORDERID_ORDERID = ao.ORDERID " + 
    "INNER JOIN bo ON OrderBook.BIDORDERID_ORDERID = bo.ORDERID " +
    "WHERE ao.ORDERID = :askOrderId"
)

我得到的错误是：

Internal Exception: Exception [EclipseLink-7158] (Eclipse Persistence
Services - 2.5.0.v20130507-3faac2b): 
org.eclipse.persistence.exceptions.ValidationException
Exception Description: Error encountered when building the @NamedQuery
[findOrderBooksPrices] from entity class [class  
org.eclipse.persistence.internal.jpa.metadata.queries.
NamedQueryMetadata].Internal Exception: java.lang.ClassCastException: 
org.eclipse.persistence.jpa.jpql.parser.NullExpression cannot be cast to 
org.eclipse.persistence.jpa.jpql.parser.IdentificationVariable. Please
see server.log for more details.

我希望在提交订单 ID 后 return 每个订单的价格 table。

感谢观看。干杯，泽布

Answer 1

猜一猜：

 query="SELECT ao.price, bo.price FROM OrderBook " +
    "INNER JOIN askorder ao " + 
    "INNER JOIN bidorder bo " +
    "WHERE ao.ORDERID = :askOrderId"

MySQL 到 JPQL 内部联接

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