Oracle

Berkeley DB Java Edition
Examples

The JE distribution comes with examples that illustrate:

using the JE programming interfaces to perform basic database operations
scenarios from the Getting Started Guide and Writing Transactional Applications
using the Direct Persistence Layer to implement common SQL queries
using JE High Availability

Building and running JE examples
Basic Example
Getting Started Examples
Writing Transactional Applications Examples
Translating SQL Queries
Examples List

Building and Running a Basic Example

Compiling and running a simple example can serve as a sanity check of the installation. Follow the instructions below to compile and run the PersonExample.

You can find the source for this example at:

JE_HOME/examples/persist/PersonExample.java

Assuming you have installed the JavaSE JDK and have verified that you have a working Java compiler, you can build PersonExample as follows.

Change to the
```
JE_HOME/examples
```
directory.

Set your CLASSPATH to include both
```
JE_HOME/lib/je-M.N.P.jar
```
and the
```
JE_HOME/examples
```
directory.

Compile PersonExample.java with the following command:
```
javac persist/PersonExample.java
```
or on Windows:
```
javac persist\PersonExample.java
```

To run PersonExample , use the following command, specifying an environment directory for the data generated by the example:

java persist.PersonExample -h <environment directory>

For example, using "." for the second parameter will write the database files into the current directory. You'll notice that a 00000000.jdb file and and je.lck file are created. This is the first log file in the environment and a lock file. If you need to delete the environment for running a different example, simply delete these two files.

When you run the program you'll see the following output. While this is not a very entertaining program, it is enough to test that you have installed JE correctly.

222-22-2222 Jack Smith
333-33-3333 Mary Smith

The other JE examples are compiled and run similarly. How to run the examples from the Getting Started Guide and Writing Transactional Applications is described in the sections below, as well as how to run the Translating SQL Queries examples. Instructions for running other examples are contained in the example's source file.

Running the Getting Started Examples

As described in the Berkeley DB Java Edition Getting Started Guide, the final examples in every chapter exist in the JE package. You can build and run these examples as follows:

Change to the
```
JE_HOME/examples
```
directory.

Set your CLASSPATH to include both
```
JE_HOME/lib/je-M.N.P.jar
```
and the
```
JE_HOME/examples
```
directories.

Compile the Getting Started examples with the following commands:
```
javac je/gettingStarted/*.java
```
or on Windows:
```
javac je\gettingStarted\*.java
```
Make a directory to contain your database environment:
```
mkdir gsgEnv
```

Load your sample database:

java je.gettingStarted.ExampleDatabasePut -h gsgEnv -i je/gettingStarted/inventory.txt  -v je/gettingStarted/vendors.txt

Perform queries against your database. To see everything in the database, use:
```
java je.gettingStarted.ExampleInventoryRead -h gsgEnv
```
To perform a query based on an inventory item's name, use:
```
java je.gettingStarted.ExampleInventoryRead -h gsgEnv -s Upo
```

Running the Writing Transactional Applications Examples

The examples in Writing Transactional Applications with Berkeley DB, Java Edition guide exist in the JE package. You can build and run these examples as follows:

Change to the
```
JE_HOME/examples
```
directory.

Set your CLASSPATH to include both
```
JE_HOME/lib/je-M.N.P.jar
```
and the
```
JE_HOME/examples
```
directories.

Compile the Transactional Applications examples with the following commands:
```
javac je/txn/*.java
```
or on Windows:
```
javac je\txn\*.java
```
Make a directory to contain your database environment:
```
mkdir txnEx
```
Run the transactional example.
```
java je.txn.TxnGuide -h txnEx
```

Running the Translating SQL Query Examples

This example shows how some common SQL queries can be implemented using the Direct Persistence Layer. It's meant to help users who are more familiar with SQL translate those approaches to the DPL. These queries include:

Basic data retrieval:: SELECT * FROM tab ORDER BY col ASC;
A prefix query:: SELECT * FROM tab WHERE col LIKE 'prefix%';
A range query, where the data type of A (as well as B) may be an int, a float, a String, etc:: SELECT * FROM tab WHERE col gt;= A AND col <= B;
An equi-join on a single primary database:: SELECT * FROM tab WHERE col1 = A AND col2 =B;
An equi-join on two primary databases combined with a filtering on "t2.col2". Note that if "t2.col2" is a secondary key, the filtering does a index lookup. Otherwise the filtering is done through database scanning:: SELECT t1.* FROM table1 t1, table2 t2 WHERE t1.col1 = t2.col1 AND t2.col2 = A;

You can build and run these examples as follows:

Change to the
```
JE_HOME/examples
```
directory.

Set your CLASSPATH to include both
```
JE_HOME/lib/je-M.N.P.jar
```
and the
```
JE_HOME/examples
```
directories.

Compile the SQL query examples with the following commands:
```
javac persist/sqlapp/*.java
```
or on Windows:
```
javac persist\sqlapp\*.java
```
Make a directory to contain your database environment:
```
mkdir sqlEnv
```
Run the SQL query examples:
```
java persist.sqlapp.SQLApp -h sqlEnv
```
To delete database files after the example exits, do:
```
java persist.sqlapp.SQLApp -h sqlEnv -d
```

List of Examples