JDBC：在同一事务中创建的PK上的外键 [英] JDBC: foreign key on PK created in same transaction

问题描述

我的MySQL数据库中有两个表，它们是这样创建的：

I have two tables in my MySQL database, which were created like this:

CREATE TABLE table1 (
  id int auto_increment,
  name varchar(10),
  primary key(id)
) engine=innodb

和

CREATE TABLE table2 (
  id_fk int,
  stuff varchar(30),
  CONSTRAINT fk_id FOREIGN KEY(id_fk) REFERENCES table1(id) ON DELETE CASCADE
) engine=innodb

（这些不是原始表。重点是table2有一个引用表1中主键的外键）

(These are not the original tables. The point is that table2 has a foreign key referencing the primary key in table 1)

现在在我的代码中，我想在一个事务中向两个表添加条目。所以我将 autoCommit 设置为false：

Now in my code, I would like to add entries to both of the tables within one transaction. So I set autoCommit to false:

    Connection c = null;        

    PreparedStatement insertTable1 = null;
    PreparedStatement insertTable2 = null;

    try {
        // dataSource was retreived via JNDI
        c = dataSource.getConnection();
        c.setAutoCommit(false);

        // will return the created primary key
        insertTable1 = c.prepareStatement("INSERT INTO table1(name) VALUES(?)",Statement.RETURN_GENERATED_KEYS);
        insertTable2 = c.prepareStatement("INSERT INTO table2 VALUES(?,?)");

        insertTable1.setString(1,"hage");
        int hageId = insertTable1.executeUpdate();

        insertTable2.setInt(1,hageId);
        insertTable2.setString(2,"bla bla bla");
        insertTable2.executeUpdate();

        // commit
        c.commit();
   } catch(SQLException e) {
        c.rollback();
   } finally {
      // close stuff
   }

我执行上面的代码，我得到一个例外：

When I execute the code above, I get an Exception:

MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails

在提交之前，似乎主键在事务中不可用。

It seems like the primary key is not available in the transaction before I commit.

我在这里遗漏了什么吗？我真的认为生成的主键应该在事务中可用。

Am I missing something here? I really think the generated primary key should be available in the transaction.

程序使用mysql-connector 5.1.14和MySQL 5.5.8在Glassfish 3.0.1上运行

The program runs on a Glassfish 3.0.1 using mysql-connector 5.1.14 and MySQL 5.5.8

非常感谢任何帮助！

问候，
hage

Regards, hage

推荐答案

您错过了返回更新ID的内容，您必须这样做：

You missed something for the returned updated id , you have to do like this :

Long hageId = null;

try {
    result = insertTable1.executeUpdate();
} catch (Throwable e) {
    ...
}

ResultSet rs = null;

try {
    rs = insertTable1.getGeneratedKeys();
    if (rs.next()) {
        hageId = rs.getLong(1);
    }
 ...

这篇关于JDBC：在同一事务中创建的PK上的外键的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！