No Two Rooms Share a Code

Create rooms with id INTEGER PRIMARY KEY, code TEXT NOT NULL UNIQUE and capacity INTEGER (NULL allowed). Inserting two rooms with the same code must fail, a room with no code must fail, and a room with a code but no capacity must be accepted.

Expected result:

Table rooms
✓ id INTEGER PRIMARY KEY
✓ code TEXT NOT NULL
✓ capacity INTEGER
✓ UNIQUE (code)
✓ Two rooms both coded T-100: rejected (UNIQUE)
✓ A room with no code: rejected (NOT NULL)
✓ A room whose capacity is unknown: accepted

Hints3 available

Topics:

CREATE TABLE

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