5.3. Compatibility between Databases

• The variants of SQL used by different database implementations are very different.
• The SQL standards define a very low common denominator, and even most SQL functions have different names and semantics in different implementations.
• If you wish to support more than one implementation, you'll probably need more than one codebase.
• It is a good idea to think what features you would need (at present and in the future) and choose one database that supports all of them.