使用外键在表中输入数据时，JDBC异常

Question

When I enter data with my java program (simple dictionary ) it throws an error:

MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails ( singlehaw . card , CONSTRAINT card_ibfk_1 FOREIGN KEY ( wordId ) REFERENCES word ( wordId ))

But when I enter data through query in command prompt I don't face any problem.

here I post my method:

public boolean insert(Card card) {
    Connection connection = MySqlUtils.getInstance().getConnection();
    PreparedStatement statement = null;
    ResultSet resultSet = null;
    int cardId = -1;
    try {
        String INSERT_INTO_TABLE_CARD_QUERY = "INSERT INTO "
                + TBL_CARD + " ("
                + STATUS + ", "
                + RATING + ", "
                + INSERT_TIME + ", "
                + DIC_ID + ", "
                + WORD_ID
                + ") VALUES (?,?,NOW(),?,?)";
        statement = connection.prepareStatement(INSERT_INTO_TABLE_WORDS_QUERY, Statement.RETURN_GENERATED_KEYS);
        statement.setString(1, card.getStatus().name());
        statement.setInt(2, card.getRating());
        statement.setInt(3, card.getDictionaryId());
        statement.setInt(4, card.getWordId());
        statement.execute();

        // get last inserted id
        resultSet = statement.getGeneratedKeys();
        if (resultSet.next())
            cardId = resultSet.getInt(1);
    } catch (SQLException e) {
        e.printStackTrace();
        return false;
    } finally {
        try {
            if (connection != null)
                connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    card.setCardId(cardId);
    return true;
}

and also scripts of creating tables:

CREATE TABLE dictionary (
dictionaryId SERIAL,
dictionary VARCHAR(128) NOT NULL,
PRIMARY KEY (dictionaryId)
) ENGINE=INNODB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

CREATE TABLE word (
wordId SERIAL,
word VARCHAR(255) NOT NULL UNIQUE, 
transcription VARCHAR(255),
PRIMARY KEY (wordId)
) ENGINE=INNODB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

CREATE TABLE card (
cardId SERIAL,
status ENUM ('EDIT', 'POSTPONED', 'TO_LEARN', 'LEARNT') NOT NULL DEFAULT 'TO_LEARN',
rating TINYINT DEFAULT '0' NOT NULL,
insert_time TIMESTAMP DEFAULT NOW(),
update_time TIMESTAMP,
dictionaryId BIGINT UNSIGNED NOT NULL,
wordId BIGINT UNSIGNED NOT NULL,
PRIMARY KEY (cardId),
FOREIGN KEY (wordId) REFERENCES word (wordId),
FOREIGN KEY (dictionaryId) REFERENCES dictionary (dictionaryId) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=INNODB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

Answer 1

Perhaps, the fact your wordID fields on the tables have different data types is affecting your program. SERIAL is an alias for Bigint. Idea discarded.

Print somwehere in the logs the actual statement being executed. Maybe there's something that's not being included.

Answer 2

Thnx guys a lot. Understood many things from this topic. Right now the problem has gone. The problem was due to populating tables via JUnit tests and because of maven my tests gone in a wrong order so it was difficult to recognize the real problem.

Answer 3

You can switch off your constraints ,execute your query, and switch constraints on.

SET FOREIGN_KEY_CHECKS=0;
... here is your sql ...
SET FOREIGN_KEY_CHECKS=1;