Question

So I’ve got a file schema.sql which contains the schema of the database and I want to create the tables accordingly when the application is deployed.

The ServletContextListener looks like this

/**
 * This class doesn't really belong to the Ui package, but it does depend on
 * servlet technology like all the other classes here, so I've just put it here for the moment.
 * 
 * The class may be moved in the future
 * 
 * When the application is deployed and started, this class connects to the database,
 * checks if the environment is compatible, checks various other things like whether
 * Core.User.HASH_ALGO or Core.User.STRING_ENCODING are supported (see Core.User for
 * details).
 */
package Ui;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletContext;

import com.mysql.jdbc.Driver;
import java.sql.*;

import java.io.*;
import java.net.URL;

/**
 * Web application lifecycle listener.
 */
public class AppContextListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        ServletContext s = sce.getServletContext();
        String db_uri = s.getInitParameter("DB_HOST");
        String db_user = s.getInitParameter("DB_USERNAME");
        String db_pass = s.getInitParameter("DB_PASSWORD");
        try {
          Connection connection = DriverManager.getConnection(db_uri, db_user, db_pass);
          //TODO check if version is compatible ;-), set app as unusable if necessary
          s.setAttribute("db", connection);
          Statement st = null;
          if(null != connection) {
              st = connection.createStatement();
              String schema = null;
              try {
                InputStream str = s.getResourceAsStream("/WEB-INF/sql/schema.sql");
                schema = readStream(str);

              }
              catch(Exception e) {
                  //TODO set global application state as unusable, with a message
              }
              finally {
                int i = st.executeUpdate(schema);
             }
          }
        } catch(SQLException e) {
            //TODO set global application state as unusable, with a message
        }
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        //TODO disconnect from the DB
    }

    protected String readStream(InputStream stream) {
        BufferedInputStream bis = new BufferedInputStream(stream);
        ByteArrayOutputStream buf = new ByteArrayOutputStream();
        try {
            int result = bis.read();
            while(result != -1) {
              byte b = (byte)result;
              buf.write(b);
              result = bis.read();
            }
        }
        catch(IOException e) {
            return null;
        }
        finally {
            return buf.toString();
        }

    }
}

and the schema like this:

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
SET AUTOCOMMIT=0;
START TRANSACTION;
SET time_zone = "+00:00";

CREATE TABLE IF NOT EXISTS `users` (
  `id` int(11) NOT NULL,
  `username` varchar(20) COLLATE utf8_bin DEFAULT NULL,
  `password` varchar(40) COLLATE utf8_bin NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `username` (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
COMMIT;

The error is:

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 ‘SET AUTOCOMMIT=0;
START TRANSACTION;

So it looks to me as if it doesn’t accept multiple commands in a shot. What is the right way to get it working? Using one single separate schema.sql is imperative.

Answer 1

I don’t have enough environment to test this, but have you tried to do this as a batch using addBatch(schema) and executeBatch()?

Otherwise, you may be stuck splitting the command up using schema.split(";") and execute one at a time. If you do this, be sure to not leave the tran open if you fall out of the loop.

Best of luck.