为什么此PreparedStaement引发mysql错误？ [重复]

Question

此问题已经在这里有了答案：

• MySQLSyntaxErrorException near “?” when trying to execute PreparedStatement2个答案

我正在通过jdbc连接在mysql数据库中进行插入，该连接可以完美连接，如果在执行PreparedStatement时，Tomcat会抛出一个SQL错误，提示以下内容：

java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?,?,?)' at line 1

问题是，当我通过一条语句进行查询时，它可以毫无问题地执行查询，这使我怀疑该错误实际上在PreparedSatement中。我在这里留下代码。

@Override
public void save(Planet planet) throws SQLException {
    String namePlanet = planet.getName();
    float massPlanet = planet.getMass();
    boolean habitablePlanet = planet.isHabitable();
    sql = "INSERT INTO planeta (nom,massa,habitable) VALUES (?,?,?)";
    PreparedStatement preparedStatement = conn.prepareStatement(sql);
    preparedStatement.setString(1, namePlanet);
    preparedStatement.setFloat(2, massPlanet);
    preparedStatement.setBoolean(3, habitablePlanet);
    preparedStatement.executeUpdate(sql);
}

我还将使代码保留PreparedStatement，因此您可以看到它确实有效。

@Override
public void save(Planet planet) throws SQLException {
    String namePlanet = planet.getName();
    float massPlanet = planet.getMass();
    boolean habitablePlanet = planet.isHabitable();
    sql = "insert into planeta(nom,massa,habitable) value('" + namePlanet + "'," + massPlanet + "," + habitablePlanet + ")";
    stmt.executeUpdate(sql);

}

请耐心等待我，我是学生，在此先感谢。

Answer 1

就像@Jens在评论中告诉我，我必须不带参数地调用executeUpdate()。

再次感谢@Jens !!

那是正确的代码：

@Override
public void save(Planet planet) throws SQLException {
    String namePlanet = planet.getName();
    float massPlanet = planet.getMass();
    boolean habitablePlanet = planet.isHabitable();
    sql = "INSERT INTO planeta (nom,massa,habitable) VALUES (?,?,?)";
    PreparedStatement preparedStatement = conn.prepareStatement(sql);
    preparedStatement.setString(1, namePlanet);
    preparedStatement.setFloat(2, massPlanet);
    preparedStatement.setBoolean(3, habitablePlanet);
    preparedStatement.executeUpdate(); // <--- Here was the error!!

}