Shulou(Shulou.com)06/01 Report--

1. Derby presentation

The reason to focus on small Derby is pure green, lightweight, small memory footprint, minutes in your machine running up, do your own need to connect to the database code practice is very convenient.

Although Mysql is also possible, isn't it good to have one more choice?

Apache Derby is a database written entirely in Java and Derby is an Open source product.

Apache Derby is very small, the core part derby.jar is only 2M, which can be used as a stand-alone database server or embedded in an application.

Official website download address: db.apache.org/derby/derby_downloads.html

Click to enter the version, pay attention to view the conditions required for Build Environment, click Download zip to extract to a random directory.

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2. Slightly configure environment variables

Derby is based on Java, you need to have Java JRE on your machine, the specific installation and configuration will not say.

Here are the system environment variables Derby needs to configure to let the system know where to find the executor for the command.

Name: DERBY_HOME Value: E:\Java\derby\db-derby-10.10.1.1-bin Joined in Path: %DERBY_HOME%\bin Add to CLASSPATH: %DERBY_HOME%\lib\derby.jar;%DERBY_HOME%\lib\derbyclient.jar;%DERBY_HOME%\lib\derbytools.jar;%DERBY_HOME%\lib\derbynet.jar

Cut to cmd under the black box and type sysinfo

At this point, the small Derby has been successfully installed on your computer, is it fast? The year, can carry on to toss.

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3. Derby operations and Java access

a. Create a database and connect (if there is a connection, there is no post-creation connection)

connect 'jdbc:derby:dedb;user=root;password=root;create=true';

b. Create a new system user table

create table t_user(uuid varchar(32), name varchar(10), age int, address varchar(40));

c. Insert some test data

insert into t_user values('B82A6C5244244B9BB226EF31D5CBE508', 'Miachel', 20, 'street 1');insert into t_user values('B82A6C5244244B9BB226EF31D5CBE509', 'Andrew', 35, 'street 1');insert into t_user values('B82A6C5244244B9BB226EF31D5CBE510', 'Orson', 47, 'street 1');insert into t_user values('B82A6C5244244B9BB226EF31D5CBE511', 'Rambo', 19, 'street 1');

Note: To operate Derby, you need to use the ij tool (similar to oracle plus). Enter ij below CMD to enter ij mode;

The path to create the database depends on your CMD path, such as C:\Users\Administrator>, where the Derby database is created;

If you are familiar with sql, there is no problem operating derby.

e. Using Derby in Java Programs

import java.sql.*; public class DerbyTest { private static String driver = "org.apache.derby.jdbc.EmbeddedDriver"; private static String protocol = "jdbc:derby:"; String dbName = "E:\\Users\\Workspaces\\Derby\\dedb"; public static void loadDriver() { try { Class.forName(driver).newInstance(); } catch (Exception e) { e.printStackTrace(); } } public void getDataFromDerby() { try { Connection conn = DriverManager.getConnection(protocol + dbName + ";user=root;password=root;create=true"); Statement statement = conn.createStatement(); ResultSet resultSet = statement.executeQuery("select * from t_user"); while (resultSet.next()) { System.out.println(resultSet.getString(1)); System.out.println(resultSet.getString(2)); } conn.close(); statement.close(); resultSet.close(); } catch (Exception e1) { e1.printStackTrace(); } } public static void main(String[] args) { DerbyTest derbyTest = new DerbyTest(); loadDriver(); derbyTest.getDataFromDerby(); }}

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