Derby database usage

Derby database is an open-source dB project under Apache. It has the following advantages over other databases:

1. fully implemented in Java

2. Support for JDBC and SQL standards

3. Only about 2 MB of all files

4. Provides embedded support and can be easily embedded into other Java projects.

5. The network database function is also provided and can be accessed in C/S mode.

 

This article briefly introduces how to use Derby:

1. Download

The Derby Project homepage is.

Ii. Installation

Derby downloads a file as a zip file. You only need to extract the file to a directory (replace derby_home here.

3. Local access

Derby can be used as a local database, which is like access. The following describes how to use the IJ tool provided by Derby to create a new database.

Create a new demo directory and run it in the demo directory:

Derby_home/bin/IJ 

Enter

Connect 'jdbc: Derby: mydemo; Create = true ';

Create a new database named mydemo and save it in the current directory. For more information about how to use IJ, enter help.

Iv. Network Access

In the demo directory, run

Java-jar derby_home/lib/derbyrun. Jar Server start

The Derby server is successfully started. The default port is 1527. Open another console and run

IJ <br/> connect 'jdbc: Derby: // localhost: 1527/mydemo ';

You can successfully connect to the mydemo database you just created. To facilitate the following test, run the following statement to create a test table and insert two pieces of data.

Create Table Test (ID int, name varchar (20); <br/> insert into test values (0, 'jack '); <br/> insert into test values (1, 'Tom ');

V. Java code access

Create a Java file with the following code:

Import Java. SQL. connection; <br/> Import Java. SQL. drivermanager; <br/> Import Java. SQL. resultset; <br/> Import Java. SQL. sqlexception; <br/> Import Java. SQL. statement; </P> <p> public class derbydemo {</P> <p> static string embeded_driver = "org. apache. derby. JDBC. embeddeddriver "; <br/> static string net_driver =" org. apache. derby. JDBC. clientdriver "; </P> <p> static string db_name =" mydemo "; <br/> static string H Ost_url = "// localhost: 1527 /"; </P> <p>/** <br/> * @ Param ARGs <br/> */<br/> Public static void main (string [] ARGs) {<br/> // todo auto-generated method stub <br/> connection conn = NULL; <br/> statement stmt = NULL; <br/> resultset rs = NULL; <br/> try {<br/> conn = getnetwrokconnect (); <br/> stmt = Conn. createstatement (); <br/> rs = stmt.exe cutequery ("select * from test"); <br/> while (RS! = NULL & RS. next () {<br/> system. out. println (RS. getstring (2); <br/>}< br/>} catch (exception ex) {<br/> system. out. println (ex. getmessage (); <br/>}finally {<br/> try {<br/> Rs. close (); <br/>}catch (exception e) {<br/>}< br/> rs = NULL; <br/> try {<br/> stmt. close (); <br/>}catch (exception e) {<br/>}< br/> stmt = NULL; <br/> try {<br/> Conn. close (); <br/>}catch (exception e) {<br/>}< br/> conn = NULL; <br/>}</P> <p> Public static connection getembededconnect () {<br/> try {<br/> class. forname (embeded_driver); <br/>} catch (classnotfoundexception e) {<br/> // todo auto-generated Catch Block <br/> throw new runtimeexception (E. getmessage (); <br/>}< br/> try {<br/> return drivermanager. getconnection ("JDBC: Derby:" + db_name); <br/>} catch (sqlexception E) {<br/> // todo auto-generated Catch Block <br/> throw new runtimeexception (E. getmessage (); <br/>}</P> <p> Public static connection getnetwrokconnect () {<br/> try {<br/> class. forname (net_driver); <br/>} catch (classnotfoundexception e) {<br/> // todo auto-generated Catch Block <br/> throw new runtimeexception (E. getmessage (); <br/>}< br/> try {<br/> return drivermanager. getconnection ("JDBC: Derby:" + host_url <br/> + db_name); <br/>} catch (sqlexception E) {<br/> // todo auto-generated Catch Block <br/> throw new runtimeexception (E. getmessage (); <br/>}</P> <p >}< br/>

Save derbydemo to the demo directory and run the following code to compile and run it to access the server through the network (Step 4 is required to start the server)

Javac-CP derby_home/lib/derbyclient. Jar derbydemo. Java <br/> JAVA-CP.; derby_home/lib/derbyclient. Jar derbydemo

To use embedded access, you only need to change getnetwrokconnect in main to getembededconnect.