Write database schema

sql/init.sql

@@ -0,0 +1,34 @@
+CREATE TABLE election (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name TEXT NOT NULL,
+    tokens INTEGER NOT NULL,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE TABLE choices (
+    text TEXT NOT NULL,
+    election_id INTEGER NOT NULL,
+    PRIMARY KEY (text, election_id),
+    FOREIGN KEY (election_id) REFERENCES election (id)
+);
+
+CREATE TABLE voters (
+    passcode TEXT NOT NULL,
+    election_id INTEGER NOT NULL,
+    PRIMARY KEY (passcode, election_id),
+    FOREIGN KEY (election_id) REFERENCES election (id)
+);
+
+CREATE TABLE votes (
+    voter_passcode TEXT NOT NULL,
+    election_id INTEGER NOT NULL,
+    choice_text TEXT NOT NULL,
+    tokens INTEGER NOT NULL,
+    calculated_vote_count GENERATED ALWAYS AS (sqrt(tokens)) VIRTUAL,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (voter_passcode, choice_text),
+    FOREIGN KEY (voter_passcode, election_id) REFERENCES voters (passcode, election_id),
+    FOREIGN KEY (choice_text, election_id) REFERENCES choices (text, election_id)
+);
+
+PRAGMA foreign_keys = ON; -- run after opening the connection so foreign key constraints are checked