Support for ENUMs

Although not a part of the SQL standard, enumerated values are a common feature in domain models, are supported in some ways by most databases, and can be expressed with the TypeScript typing system. Enums in databases currently supported by sql-ts come at least in three forms:

1. The PostgreSQL TYPE ... AS ENUM, which is a named, stand-alone data type that can be shared by multiple columns in different tables. This pretty clearly maps to a TypeScript string enum, which can then be referred to in the individual table interfaces.
2. The MySQL ENUM(...) column type, which is anonymous. It is conceptually similar to a TypeScript string union (ENUM('a', 'b', 'c') -> 'a' | 'b' | 'c'), but perhaps using a string enum for these as well would be desirable for consistency?
3. Using a check constraint to limit the column to certain values – the only enum implementation available for SQL Server and SQLite, and preferred by some with PostgreSQL. I don’t know if handling these would be feasible, as check constraints are a very expressive construct, and detecting whether one is to be considered an “enum” or not would probably be difficult.

[rmp135]

ENUM support for Postgres has been added to 1.5.0. I don’t have a lot of experience with Postgres but I’ve think I got it working. If you reference an ENUM in a different schema or if multiple exist with the same name, use the schemaAsNamespace config option.

I may implement MySQL ENUMs as string unions as was suggested in the original ticket if there’s more interest.

[daniellemburgLWT]

Awesome. Thanks alot!