Add database schema for trips, students, parents, and constraints

schema.sql

@@ -0,0 +1,45 @@
+DO $$ BEGIN
+    CREATE TYPE constraint_kind AS ENUM ('happy', 'ok', 'never');
+EXCEPTION WHEN duplicate_object THEN NULL;
+END $$;
+
+DO $$ BEGIN
+    CREATE TYPE constraint_level AS ENUM ('student', 'parent', 'admin');
+EXCEPTION WHEN duplicate_object THEN NULL;
+END $$;
+
+CREATE TABLE IF NOT EXISTS trips (
+    id BIGSERIAL PRIMARY KEY,
+    name TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS trip_admins (
+    id BIGSERIAL PRIMARY KEY,
+    trip_id BIGINT NOT NULL REFERENCES trips(id) ON DELETE CASCADE,
+    email TEXT NOT NULL,
+    UNIQUE(trip_id, email)
+);
+
+CREATE TABLE IF NOT EXISTS students (
+    id BIGSERIAL PRIMARY KEY,
+    trip_id BIGINT NOT NULL REFERENCES trips(id) ON DELETE CASCADE,
+    name TEXT NOT NULL,
+    email TEXT NOT NULL,
+    UNIQUE(trip_id, email)
+);
+
+CREATE TABLE IF NOT EXISTS parents (
+    id BIGSERIAL PRIMARY KEY,
+    student_id BIGINT NOT NULL REFERENCES students(id) ON DELETE CASCADE,
+    email TEXT NOT NULL,
+    UNIQUE(student_id, email)
+);
+
+CREATE TABLE IF NOT EXISTS roommate_constraints (
+    id BIGSERIAL PRIMARY KEY,
+    student_a_id BIGINT NOT NULL REFERENCES students(id) ON DELETE CASCADE,
+    student_b_id BIGINT NOT NULL REFERENCES students(id) ON DELETE CASCADE,
+    kind constraint_kind NOT NULL,
+    level constraint_level NOT NULL,
+    UNIQUE(student_a_id, student_b_id, level)
+);