Converting a Non-CDB database to a Pluggable Database (PDB) is a common modernization step when moving to the multitenant architecture introduced in Oracle Database 12c and later versions like Oracle Database 19c.
The strategic goal is to migrate the standalone database into a Container Database (CDB) as a PDB, enabling centralized management, consolidation, and simplified patching.

When converting a Non-CDB database into a PDB, two environments are involved:

• Source → the existing Non-CDB database
• Target → the Container Database (CDB) where the new PDB will be created

Non-CDB to PDB Conversion – Where Each Step Runs

Step	Command	Run On	Container
1	DBMS_PDB.DESCRIBE	Source	Non-CDB
2	Copy XML file	OS	From Source → Target
3	CHECK_PLUG_COMPATIBILITY	Target	CDB$ROOT
4	CREATE PLUGGABLE DATABASE	Target	CDB$ROOT
5	Open PDB restricted	Target	CDB$ROOT
6	ALTER SESSION SET CONTAINER	Target	New PDB
7	noncdb_to_pdb.sql	Target	New PDB
8	utlrp.sql	Target	New PDB

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Step-by-Step With Exact Location

Step 1 — Generate XML Manifest

Run on the source Non-CDB database.

BEGIN
 DBMS_PDB.DESCRIBE('/tmp/noncdb.xml');
END;
/

Location:

• Database → Source
• Type → Non-CDB

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Step 2 — Copy XML File

Copy the manifest file to the target server.

Example:

scp /tmp/noncdb.xml oracle@targetserver:/tmp/

Location:

• OS level
• Source → Target

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Step 3 — Check Compatibility

Run on the target CDB.

Connect to the root container.

sqlplus / as sysdba

Check container:

SHOW CON_NAME;

Expected:

CDB$ROOT

Run compatibility check:

SET SERVEROUTPUT ONDECLARE
compatible BOOLEAN;
BEGIN
compatible := DBMS_PDB.CHECK_PLUG_COMPATIBILITY(
pdb_descr_file => '/tmp/noncdb.xml',
pdb_name => 'NONCDBPDB');IF compatible THEN
 DBMS_OUTPUT.PUT_LINE('Compatible');
END IF;
END;
/

Location:

• Database → Target
• Container → CDB$ROOT

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Step 4 — Create the PDB

Run on the target CDB root.

CREATE PLUGGABLE DATABASE NONCDBPDB
USING '/tmp/noncdb.xml'
COPY
FILE_NAME_CONVERT =
('/u01/oradata/noncdb/',
 '/u01/oradata/cdb1/noncdbpdb/');

Location:

• Database → Target
• Container → CDB$ROOT

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Step 5 — Open PDB in Restricted Mode

ALTER PLUGGABLE DATABASE NONCDBPDB OPEN RESTRICTED;

Location:

• Database → Target
• Container → CDB$ROOT

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Step 6 — Switch to the New PDB

ALTER SESSION SET CONTAINER = NONCDBPDB;

Location:

• Database → Target
• Container → New PDB

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Step 7 — Run Conversion Script

@$ORACLE_HOME/rdbms/admin/noncdb_to_pdb.sql

Location:

• Database → Target
• Container → New PDB

This converts the non-CDB data dictionary to PDB format.

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Step 8 — Recompile Invalid Objects

@$ORACLE_HOME/rdbms/admin/utlrp.sql

Location:

• Database → Target
• Container → New PDB

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Important Considerations

1. Character Set Must Match

Non-CDB and CDB should have compatible character sets.

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2. Option and Component Matching

Installed components should match.

Check:

SELECT comp_name, version FROM dba_registry;

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3. Time Zone Version

Mismatch can cause plug-in violations.

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4. Undo Mode

Target CDB should use Local Undo Mode.

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Alternative Methods (Oracle Supported)

Method	Use Case
noncdb_to_pdb.sql	Most common
Data Pump	Cross platform
Transportable Tablespace	Large DB migration
RMAN Duplicate	Migration scenarios