Oracle 21c XE Usage Guide

Oracle 21c XE Usage Guide | Generated by AI

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Question: How to use Oracle Database 21c Express Edition (XE)?

Answer:

Oracle XE 21c is a lightweight free Oracle database for development/testing. The typical workflow is:

Install XE
   ↓
Start database service
   ↓
Connect with SQL*Plus / SQL Developer
   ↓
Create user/schema
   ↓
Create tables
   ↓
Connect from Java/Python apps

Oracle XE 21c creates:

Container database: XE
Pluggable database: XEPDB1
Listener: default port 1521
Enterprise Manager Express: usually 5500 (Oracle Docs)

1. Install Oracle Database XE 21c

Windows

Download and run installer:

setup.exe

Run as Administrator. The installer creates database SID:

XE

and asks you to set passwords for:

SYS
SYSTEM
PDBADMIN

(Oracle Docs)

2. Check Oracle services

Windows:

Win + R

services.msc

Find:

OracleServiceXE
OracleOraDB21Home*TNSListener

Start them.

(Oracle)

3. Connect using SQL*Plus

Open terminal:

sqlplus / as sysdba

You should see:

SQL>

Check database:

select name from v$database;

Output:

XE

Check PDB:

show pdbs;

Example:

CON_ID CON_NAME   OPEN MODE

2      XEPDB1     READ WRITE

4. Open PDB if needed

Oracle 21c uses multitenant architecture.

sqlplus / as sysdba

Run:

alter pluggable database XEPDB1 open;

Make it auto-open:

alter pluggable database XEPDB1 save state;

5. Create application user

Do not use SYSTEM for applications.

Switch to PDB:

alter session set container=XEPDB1;

Create user:

create user app identified by password123;

Grant permissions:

grant connect, resource to app;

For development:

grant unlimited tablespace to app;

6. Connect as your user

Connection string:

username: app
password: password123

host: localhost
port: 1521
service: XEPDB1

SQL*Plus:

sqlplus app/password123@localhost:1521/XEPDB1

7. Create tables

Example:

create table users (
    id number generated by default as identity,
    name varchar2(100),
    email varchar2(200),
    created_at timestamp default current_timestamp,
    primary key(id)
);

Insert:

insert into users(name,email)
values('Alice','alice@test.com');

commit;

Query:

select * from users;

8. Use Oracle from Java Spring Boot

Maven:

<dependency>
    <groupId>com.oracle.database.jdbc</groupId>
    <artifactId>ojdbc11</artifactId>
    <version>23.8.0.25.04</version>
</dependency>

application.yml

spring:
  datasource:
    url: jdbc:oracle:thin:@localhost:1521/XEPDB1
    username: app
    password: password123
    driver-class-name: oracle.jdbc.OracleDriver

  jpa:
    database-platform: org.hibernate.dialect.OracleDialect

Then:

@Entity
class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Long id;

    String name;
}

9. Use Oracle SQL Developer

Install:

Oracle SQL Developer

Create connection:

Name:
XE Local

Username:
app

Password:
password123

Hostname:
localhost

Port:
1521

Service name:
XEPDB1

Test:

Success

10. Useful DBA commands

Show users

select username from dba_users;

Show tables

select table_name from user_tables;

Current user

show user;

Shutdown

shutdown immediate;

Startup

startup;

11. Docker option (often easier)

For development, Oracle XE in Docker is usually cleaner:

docker run \
-d \
--name oracle21c \
-p 1521:1521 \
-e ORACLE_PASSWORD=<PASSWORD> \
gvenzl/oracle-xe

Connect:

localhost:1521/XEPDB1

For a Java/Spring engineer, the learning path I would use:

SQL basics
 ↓
Oracle schema/user model
 ↓
PLSQL procedures
 ↓
Indexes + execution plans
 ↓
Spring Boot + Oracle JDBC
 ↓
Oracle RAC/Data Guard concepts

Oracle is still common in banking/enterprise systems, especially with Java stacks. (Oracle)

References:

Oracle Database XE 21c Installation Guide (Oracle Docs)
Oracle XE Quick Start (Oracle)

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