executeQuery始终为空

Question

我正在尝试从数据库中获取数据，但什么都没得到。问题是

  

ResultSet resultSet = statement.executeQuery（readQuery）;

总是空着的。并且

  

while（resultSet.next（））

永远不会执行。 非常感谢任何帮助

public class DB {

    public Connection connect() {
        Connection connection = null;
        try {
            String databaseURL = "jdbc:derby://localhost:1527/DB;create=true;user=user;password=password";
            Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
            connection = DriverManager.getConnection(databaseURL);
        } 
        catch (ClassNotFoundException | InstantiationException | IllegalAccessException | SQLException ex) {
            Logger.getLogger(DB.class.getName()).log(Level.SEVERE, null, ex);
        }
        return connection;
    } 

    ArrayList read(Connection connection, String table, String column, String value) {
        ArrayList results = new ArrayList();  
        Statement statement = null;

        try {
            statement = connection.createStatement();
            String readQuery = "select * from " + table + " where " + column + " = '" + value + "'";

            out.print(readQuery);
            ResultSet resultSet = statement.executeQuery(readQuery); 

            while (resultSet.next()) {
                ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
                int numberOfColumns = resultSetMetaData.getColumnCount();
                out.print("Read\n");
                for (int i = 1; i < numberOfColumns + 1; i++) {
                    results.add(resultSet.getString(i));   
                }
            }
            statement.close(); 
            connection.close();
        }
        catch (SQLException ex) {   
        }
        return results;
    }
}