# Database — Golden Rules

## Naming

- `snake_case` only for tables and columns.
- Good: `user_profile`, `payment_order`, `user_session`.
- Forbidden prefixes: `tbl_`, `t_`.

## Required columns on business tables

```
id
created_at
updated_at
deleted_at
```

## Types

- Never `varchar(5000)` as a habit.
- Prefer bounded `varchar(n)`.
- `TEXT` only when necessary (long content bodies).
- Timestamps: `timestamptz`.

## Keys & indexes

- Every foreign key indexed.
- Unique business keys enforced with UNIQUE.

## Migrations

- Schema change without migration = incomplete feature.
- Migrations live in `apps/api/migrations/`.
- Provide Up and Down when tool supports it.

## Soft delete

- Default: set `deleted_at`, do not hard delete user content in MVP.
- Queries must filter `deleted_at IS NULL` unless explicitly including deleted.