# Installing Oracle 21c Express Edition on Windows

## Overview

Oracle 21c Express Edition (XE) is free to use with the following limitations:
- 2 CPU threads
- 2 GB RAM for database
- 12 GB user data

For ROA installations with up to 50 companies, XE is sufficient.

---

## Download

1. Go to Oracle XE Downloads:
   https://www.oracle.com/database/technologies/xe-downloads.html

2. Download **OracleXE213_Win64.zip** (~1.5 GB)
   - Requires Oracle account (free registration)

3. Verify download integrity (optional):
   ```powershell
   Get-FileHash OracleXE213_Win64.zip -Algorithm SHA256
   ```

---

## System Requirements

| Requirement | Minimum | Recommended |
|-------------|---------|-------------|
| OS | Windows 10/11, Server 2016+ | Windows Server 2019+ |
| RAM | 4 GB | 8 GB |
| Disk | 15 GB | 50 GB |
| CPU | 2 cores | 4 cores |

---

## Installation

### Step 1: Extract ZIP

```powershell
Expand-Archive OracleXE213_Win64.zip -DestinationPath C:\OracleXE_Install
```

### Step 2: Run Installer

1. Open Command Prompt or PowerShell **as Administrator**

2. Navigate to extracted folder:
   ```powershell
   cd C:\OracleXE_Install\Disk1
   ```

3. Run setup:
   ```powershell
   .\setup.exe
   ```

### Step 3: Installation Wizard

1. **Welcome Screen** - Click Next

2. **License Agreement** - Accept and click Next

3. **Oracle Home Location**
   - Default: `C:\app\oracle\product\21c\dbhomeXE`
   - Keep default unless disk space is an issue

4. **Database Passwords**
   - Enter password for SYS and SYSTEM: `romfastsoft`
   - Confirm password
   - **Important:** Remember this password!

5. **Summary** - Review and click Install

6. **Installation Progress** - Wait (~10-20 minutes)

7. **Finish** - Note the connection information:
   - Multitenant container database: XE
   - Pluggable database: XEPDB1
   - EM Express URL: https://localhost:5500/em/

---

## Post-Installation Configuration

### Verify Services Running

Open Services (services.msc) and verify:

| Service | Status | Startup Type |
|---------|--------|--------------|
| OracleServiceXE | Running | Automatic |
| OracleOraDB21Home1TNSListener | Running | Automatic |

Or via PowerShell:
```powershell
Get-Service Oracle* | Format-Table Name, Status, StartType
```

### Test Connection

```powershell
# Set Oracle environment
$env:ORACLE_HOME = "C:\app\oracle\product\21c\dbhomeXE"
$env:PATH = "$env:ORACLE_HOME\bin;$env:PATH"

# Test connection to CDB
sqlplus system/romfastsoft@localhost:1521/XE

# Test connection to PDB (for applications)
sqlplus system/romfastsoft@localhost:1521/XEPDB1
```

Expected output:
```
Connected to:
Oracle Database 21c Express Edition Release 21.0.0.0.0 - Production
Version 21.3.0.0.0

SQL>
```

## CDB/PDB Architecture

Oracle XE uses Container Database (CDB) architecture:

```
+---------------------------------------------+
|              CDB: XE                        |
|  +---------------------------------------+  |
|  |  CDB$ROOT - System, SYS objects       |  |
|  +---------------------------------------+  |
|  +---------------------------------------+  |
|  |  PDB$SEED - Template (read-only)      |  |
|  +---------------------------------------+  |
|  +---------------------------------------+  |
|  |  XEPDB1 - Application Data (ROA)      |  |
|  +---------------------------------------+  |
+---------------------------------------------+
```

| Container | Purpose | Connect To |
|-----------|---------|------------|
| XE (CDB$ROOT) | Administration, SYS | Admin only |
| XEPDB1 | Application data | ROA applications |

> **Important:** Always connect to **XEPDB1** for ROA operations, not XE!

---

## Verify PDB Status

```sql
-- Connect as SYSDBA
sqlplus sys/romfastsoft@localhost:1521/XE as sysdba

-- Check PDB status
SELECT name, open_mode FROM v$pdbs;

-- Expected output:
-- NAME      OPEN_MODE
-- --------- ----------
-- PDB$SEED  READ ONLY
-- XEPDB1    READ WRITE
```

If XEPDB1 is MOUNTED (not READ WRITE):
```sql
ALTER PLUGGABLE DATABASE XEPDB1 OPEN;
ALTER PLUGGABLE DATABASE XEPDB1 SAVE STATE;
```

---

## Ce NU trebuie făcut manual

Următoarele sunt create **automat** de scriptul `01-setup-database.ps1`:

| Component | Script |
|-----------|--------|
| Tablespace ROA | `01-setup-database.ps1` |
| DMPDIR directory | `01-setup-database.ps1` |
| Password profile (UNLIMITED) | `01-setup-database.ps1` |
| User CONTAFIN_ORACLE | `01-setup-database.ps1` |
| sqlnet.ora (client vechi) | `01-setup-database.ps1` |

**NU rula manual comenzile SQL pentru acestea** - scripturile le fac automat!

---

## Enterprise Manager Express

Access EM Express web interface:
```
https://localhost:5500/em/
```

Login:
- Username: system
- Password: romfastsoft
- Container: XEPDB1 (or leave empty for CDB)

---

## Memory Configuration

Check current memory settings:
```sql
SHOW PARAMETER memory;
SHOW PARAMETER sga;
SHOW PARAMETER pga;
```

XE defaults (cannot exceed due to license):
- SGA: 2 GB max
- PGA: 2 GB max

For better performance within limits:
```sql
-- Automatic memory management
ALTER SYSTEM SET MEMORY_TARGET = 2G SCOPE = SPFILE;
ALTER SYSTEM SET MEMORY_MAX_TARGET = 2G SCOPE = SPFILE;
```

---

## Troubleshooting

### OracleServiceXE Not Starting

1. Check Windows Event Viewer for errors
2. Verify disk space (need 15+ GB free)
3. Check Oracle alert log:
   ```powershell
   Get-Content C:\app\oracle\diag\rdbms\xe\XE\trace\alert_XE.log -Tail 50
   ```

### Cannot Connect to XEPDB1

```sql
-- Connect to CDB
sqlplus sys/romfastsoft@localhost:1521/XE as sysdba

-- Check PDB status
SELECT name, open_mode FROM v$pdbs;

-- Open if mounted
ALTER PLUGGABLE DATABASE XEPDB1 OPEN;
ALTER PLUGGABLE DATABASE XEPDB1 SAVE STATE;
```

### ORA-12514: TNS listener does not know of service

```powershell
# Check listener status
lsnrctl status
lsnrctl services

# Restart listener
lsnrctl stop
lsnrctl start
```

### Uninstall Oracle XE

If needed, run the universal installer in deinstall mode:
```powershell
C:\app\oracle\product\21c\dbhomeXE\deinstall\deinstall.bat
```

Or via Control Panel > Programs and Features.

---

## Next Steps

After Oracle XE installation:

1. Copy `config.example.ps1` to `config.ps1`
2. Edit `config.ps1` with your settings
3. Run `01-setup-database.ps1`

See main `README.md` for complete workflow.

---

**Last Updated:** 2026-01-28
**Project:** ROMFASTSQL - Oracle XE Installation Guide