Question

我已就此错误探讨了大量问题和文档，似乎无法找到我的错误。错误在这一行：

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: 
Cannot add or update a child row: a foreign key constraint fails (`flutweets`.`refs`,    
CONSTRAINT `refs_ibfk_1` FOREIGN KEY (`id`) REFERENCES `tweets` (`id`))

数据库是MySQL，我使用Workbench来检查它;我也知道所有数据库引擎都是InnoDB，而Row Formats是Compact。我有三个表：推文，主题标签和引用。这是我创建表格的地方：

tweets Table

Statement stmt = null;
    try {
        stmt = connection.createStatement();
        stmt.executeUpdate("CREATE TABLE " + TWEETS_TABLE + "("
                + TWEETS_ID + " BIGINT NOT NULL AUTO_INCREMENT,"
                + TWEETS_TIME + " VARCHAR(255),"
                + TWEETS_USER + " VARCHAR(255),"
                + TWEETS_TEXT + " VARCHAR(255) NOT NULL,"
                + TWEETS_LOCATION + " VARCHAR(255),"
                + TWEETS_CITY + " VARCHAR(255),"
                + TWEETS_PROVINCE + " VARCHAR(255),"
                + TWEETS_COUNTRY + " VARCHAR(255),"
                + TWEETS_TIME_ZONE + " VARCHAR(255),"
                + TWEETS_LATITUDE + " DECIMAL(20,16),"
                + TWEETS_LONGITUDE + " DECIMAL(20,16),"
                + "PRIMARY KEY (" + TWEETS_ID + ")"
                + ")");
       . . .

hashtags Table

Statement stmt = null;
    try {
        stmt = connection.createStatement();
        stmt.executeUpdate("CREATE TABLE " + HASHTAG_TABLE + "("
                + HASHTAG_ID + " BIGINT NOT NULL AUTO_INCREMENT,"
                + HASHTAG_TEXT + " VARCHAR(255),"
                + TWEETS_ID + " BIGINT NOT NULL,"
                + "PRIMARY KEY (" + HASHTAG_ID + ")," 
                + "FOREIGN KEY (" + TWEETS_ID + ")"
                + "REFERENCES " + TWEETS_TABLE
                + "(" + TWEETS_ID + ")" 
                + ")");
      . . .

references Table

Statement stmt = null;
    try {
        stmt = connection.createStatement();
        stmt.executeUpdate("CREATE TABLE " + REF_TABLE + "("
                + REF_ID + " BIGINT NOT NULL AUTO_INCREMENT,"
                + REF_TEXT + " VARCHAR(255),"
                + TWEETS_ID + " BIGINT NOT NULL,"
                + "PRIMARY KEY (" + REF_ID + ")," 
                + "FOREIGN KEY (" + TWEETS_ID + ")"
                + "REFERENCES " + TWEETS_TABLE
                + "(" + TWEETS_ID + ")" 
                + ")");

以下是我用来插入的语句和插入它们的方法（我正在使用预处理语句）：

/* INITIALIZE PREPARED STATEMENTS */

// Tweets
private static final String TWEETS_INSERT = "INSERT INTO " + TWEETS_TABLE
        + " (" + TWEETS_TIME + ", " + TWEETS_USER + ", " + TWEETS_TEXT + ", " + TWEETS_LOCATION + ", " + TWEETS_CITY + ", " + TWEETS_PROVINCE + ", "
        + TWEETS_COUNTRY + ", " + TWEETS_TIME_ZONE + ", " + TWEETS_LATITUDE + ", " + TWEETS_LONGITUDE + ")"
        + " VALUES(?,?,?,?,?,?,?,?,?,?)";
private PreparedStatement tweetsStatement;

// Hashtags
private static final String HASHTAGS_INSERT = "INSERT INTO " + HASHTAG_TABLE
        + " (" + HASHTAG_TEXT + ", " + TWEETS_ID + ")" + " VALUES(?,?)";
private PreparedStatement hashStatement;

// References
private static final String REF_INSERT = "INSERT INTO " + REF_TABLE
        + " (" + REF_TEXT + ", " + TWEETS_ID + ")" + " VALUES(?,?)";
private PreparedStatement refStatement;

public void insertHashtag（FluTweet tweet，int hashIndex，Integer tweetID）{

    // Pull all of the Hashtag's relevant elements.

    String hashText =  tweet.getHashtag(hashIndex);

    try {
        hashStatement.setString(1, hashText);
        hashStatement.setString(2, tweetID.toString());

        //INSERT HASHTAG INTO TABLE
        hashStatement.executeUpdate();

    } catch (SQLException e) {
        e.printStackTrace();
    }

}

public void insertReference(FluTweet tweet, int referenceIndex, Integer tweetID) {

    // Pull all of the Reference's relevant elements.

    String refText =  tweet.getReference(referenceIndex);

    try {
        refStatement.setString(1, refText);
        refStatement.setString(2, tweetID.toString());

        //INSERT REFERENCE INTO TABLE
        refStatement.executeUpdate();

    } catch (SQLException e) {
        e.printStackTrace();
    }

}

我不知道为什么这不起作用，任何帮助都会非常感激。就像我说的那样，我已经探测了很多其他帖子，但找不到相关的帮助。

Answer 1

<强>背景

我找到了自己问题的答案。任何实际的数据库处理都不是问题。事实证明，当我传递id用作标签和引用中的外来id时，我从主类中的计数器获取我的id;每个新推文都有一个数字与每个主题标签和该推文的引用一起使用，该推文稍后将用作外键。该外键将引用tweets表中的主键，该表自动递增。

以下是问题：

事实证明，当你自动增加时，MySQL NOT 零索引;第一个值为零，然后是一个，然后是两个，等等。相反，它从一个开始。因此，当我尝试使用外键引用主键时，对于我指定的每条推文（外键），从零开始的计数器与推文表（主键）中的自动递增推文ID不正确匹配。

因此，我总是被一个关闭。

我希望这有助于任何可能遇到类似问题的人。

Answer 2

如果我们没有设置有效的子类对象主键值，那么我们可以看到 MySQLIntegrityConstraintViolationException 。如果我们忽略子类对象的主键值，那么基于设置的配置hibernate pojo / hbm.xml文件第一级缓存（session）会将其刷新为数据库。

MySQLIntegrityConstraintViolationException：无法添加或更新子行：外键约束失败

2 个答案: