Convert FDB to MDF

Applications that require Microsoft SQL Server cannot open a Firebird .fdb database directly, so the data must be migrated into a new SQL Server database whose primary file is .mdf. This is a database migration, not a file-extension change, and it may require rewriting schema objects and application queries.

What the FDB format is

.fdb is the usual file extension for a Firebird relational database used by desktop, embedded, and server-based applications. It can contain tables, views, indexes, triggers, stored procedures, generators (sequences), users, and Firebird-specific metadata.

Firebird versions, connection settings, character sets, and server permissions affect compatibility. Do not open or modify an FDB with a text editor, hex editor, or generic file converter. A live database file should not be copied while Firebird is writing to it.

What the MDF format is

.mdf is the primary data file created by Microsoft SQL Server. It normally stores table data, indexes, and database metadata; SQL Server usually stores transaction-log data in a separate .ldf file. MDF is suitable when the destination application requires SQL Server, SQL Server Express, or SQL Server LocalDB.

An MDF file is not a portable interchange format and cannot contain an unchanged Firebird database. SQL Server must create the destination database and its MDF file; renaming an FDB to MDF will not work.

Desktop conversion with a migration tool

A dedicated database migration utility is usually more suitable than a file converter. Full Convert Enterprise supports Firebird-to-SQL Server migrations and can transfer tables and commonly supported schema elements. ESF Database Migration Toolkit is another desktop option. Check the current product documentation for supported Firebird and SQL Server versions, because feature coverage varies by release.

1. Stop the Firebird application and make a verified backup with gbak. Restore that backup to a test Firebird database when possible; use the restored database as the migration source rather than copying a live FDB.
2. Install the required Firebird client and ODBC driver, matching the database and operating-system architecture. Configure and test a DSN or connection to the restored Firebird database with an account that can read all required tables and metadata.
3. Install a supported SQL Server edition. Create an empty destination database in SQL Server Management Studio through Object Explorer → Databases → New Database. SQL Server creates the .mdf and .ldf files using its configured file locations.
4. In the migration utility, select Firebird as the source and SQL Server as the destination. Enter the Firebird connection details, select the target SQL Server instance and database, and review the proposed table and column mappings.
5. Inspect conversions for Boolean values, NUMERIC precision and scale, text and blob fields, timestamps, character sets, quoted identifiers, reserved words, and NULL behavior. Map Firebird generators to SQL Server identity columns or sequences where appropriate.
6. Run the migration into the test database. Review warnings and generated SQL rather than assuming that every index, constraint, default, or key was transferred correctly.
7. Recreate or manually convert views, triggers, stored procedures, generators, permissions, and scheduled jobs. Firebird PSQL is different from SQL Server T-SQL, so procedural objects and trigger logic generally require editing.
8. Compare source and destination row counts, primary-key values, and important aggregates. Test foreign keys, indexes, transactions, character handling, application queries, and backup and restore procedures before changing the production connection.

Migration with SQL Server tools and ODBC

For a smaller database, SQL Server Management Studio can start the SQL Server Import and Export Wizard through Tasks → Import Data. Select the Firebird ODBC DSN as the source, SQL Server as the destination, map the tables and columns, and run the package.

The wizard is primarily a data-copy tool. It may create basic tables but normally does not translate Firebird stored procedures, triggers, generators, permissions, or all constraints. Save the package or use an ODBC/JDBC extraction script when the migration must be repeatable; the destination MDF is still produced by SQL Server, not by the script.

Compatibility and online converter limits

Firebird and SQL Server differ in data types, identity generation, collations, case sensitivity, transaction behavior, cascade actions, reserved words, and procedural SQL. A migration can preserve the rows without preserving identical Firebird behavior. Test precision-sensitive numeric values, timestamps, large objects, Unicode text, generated keys, and application transaction logic.

No general online FDB-to-MDF converter is suitable for a production database. An FDB is a server-managed database file, and uploading it exposes its contents while online services rarely provide reliable translation of schema, permissions, triggers, or stored procedures. Use a local migration tool or a controlled export/import process; only consider an online service for non-sensitive exported data after verifying its Firebird and SQL Server support.