Add "NOT NULL" constraints to database columns

database/init_database.sql

@@ -55,8 +55,8 @@ CREATE TABLE IF NOT EXISTS scores.sports(
 CREATE TABLE IF NOT EXISTS scores.divisions(
         division_id BIGINT GENERATED ALWAYS AS IDENTITY,
         division_name TEXT NOT NULL,
-        gender VARCHAR(1) CHECK (gender IN ( 'F', 'M' ) ),
-        sport_id BIGINT,
+        gender VARCHAR(1) NOT NULL CHECK (gender IN ( 'F', 'M' ) ),
+        sport_id BIGINT NOT NULL,
         currently_active BOOLEAN DEFAULT TRUE,
         PRIMARY KEY(division_id),
         CONSTRAINT fk_sport
@@ -67,7 +67,7 @@ CREATE TABLE IF NOT EXISTS scores.divisions(
 CREATE TABLE IF NOT EXISTS scores.teams(
         team_id BIGINT GENERATED ALWAYS AS IDENTITY,
         team_name TEXT NOT NULL,
-        sport_id BIGINT,
+        sport_id BIGINT NOT NULL,
         currently_active BOOLEAN DEFAULT TRUE,
         PRIMARY KEY(team_id),
         CONSTRAINT fk_sport
@@ -83,14 +83,14 @@ CREATE TABLE IF NOT EXISTS scores.seasons(
 
 CREATE TABLE IF NOT EXISTS scores.games(
         game_id BIGINT GENERATED ALWAYS AS IDENTITY,
-        division_id BIGINT,
-        season_id BIGINT,
-        game_date DATE,
-        team1_id BIGINT,
-        team2_id BIGINT,
-        team1_score INTEGER,
-        team2_score INTEGER,
-        submitter_id BIGINT,
+        division_id BIGINT NOT NULL,
+        season_id BIGINT NOT NULL,
+        game_date DATE NOT NULL,
+        team1_id BIGINT NOT NULL,
+        team2_id BIGINT NOT NULL,
+        team1_score INTEGER NOT NULL,
+        team2_score INTEGER NOT NULL,
+        submitter_id BIGINT NOT NULL,
         updated_timestamp TIMESTAMP WITH TIME ZONE DEFAULT now(),
         PRIMARY KEY(game_id),
         CONSTRAINT fk_division