Question

我想了解下面显示的代码

Criteria criteria = session.createCriteria(Payables.class);
            criteria.add(Restrictions.eq("companyId", companyId));

        criteria.createAlias("makePayment", "makePayment");

        if (creditorId != null) {
            criteria.createAlias("makePayment.creditor", "creditor");
            criteria.add(Restrictions.eq("creditor.id", creditorId));
        }

            criteria.add(Restrictions.eq("journalEntryId", journalEntryId));

我确实知道createCriteria会做什么，但添加createAlias会让我感到困惑。我已经阅读了文档，但一切仍然模糊不清。

你能告诉我上面的代码如何使用mysql语句？

Answer 1

    Criteria criteria = session.createCriteria(Payables.class);
    // select * from Payables p;

    criteria.add(Restrictions.eq("companyId", companyId));
    // where p.companyId = :companyId

    criteria.createAlias("makePayment", "makePayment");
    // inner join Payement makePayment on makePayement.payables_id = p.id

    if (creditorId != null) {
        criteria.createAlias("makePayment.creditor", "creditor");
        // inner join Creditor c on c.payement_id = makePayement.id
        criteria.add(Restrictions.eq("creditor.id", creditorId));
        // where c.id = :creditorId
    }

    criteria.add(Restrictions.eq("journalEntryId", journalEntryId));
    // where p.journalEntryId = :journalEntryId

结果是：

    select * from Payables p
    inner join Payement makePayment on makePayement.payables_id = p.id
    inner join Creditor c on c.payement_id = makePayement.id
    where p.companyId = :companyId
    and c.id = :creditorId
    and p.journal_entry_id = :journalEntryId

对于表名，使用实体的@Table注释中的值，对于列名，使用位于字段或getter上的@Column名称值，对于join中使用的列名，使用@中的值位于@OneToMany或@ManyToOne注释附近的JoinColumn注释

Answer 2

createAlias添加了加入

类似

...
FROM Payables p1
     JOIN Payment as p2 ON p2.paybles_id=p1.id
...

然后，您可以使用联接表在WHERE部分

中添加条件

下面显示的标准代码的等效mysql语句是什么

2 个答案: