Improve SQL

models/sessions.go

@@ -61,27 +61,17 @@ func (ss *SessionService) Create(userID int) (*Session, error) {
 		Token:     token,
 		TokenHash: hash(token),
 	}
-
 	row := ss.DB.QueryRow(`
-    UPDATE sessions
-    SET token_hash = $2
-    WHERE user_id = $1
-    RETURNING id;
+    INSERT INTO sessions (user_id, token_hash)
+		VALUES ($1, $2) ON CONFLICT (user_id) DO
+		UPDATE
+		SET token_hash = $2
+		RETURNING id;
   `, session.UserID, session.TokenHash)
 	err = row.Scan(&session.ID)
-	if err == sql.ErrNoRows {
-		row = ss.DB.QueryRow(`
-      INSERT INTO sessions (user_id, token_hash)
-      VALUES ($1, $2)
-      RETURNING id;
-    `, session.UserID, session.TokenHash)
-		err = row.Scan(&session.ID)
-	}
-
 	if err != nil {
 		return nil, fmt.Errorf("create: %w", err)
 	}
-
 	return &session, nil
 }
 
@@ -97,20 +87,19 @@ func (ss *SessionService) Delete(token string) error {
 func (ss *SessionService) User(token string) (*User, error) {
 	token_hash := hash(token)
 	var user User
+
 	row := ss.DB.QueryRow(`
-    SELECT (user_id) FROM sessions WHERE token_hash = $1;
+    SELECT users.id,
+      users.email,
+      users.password_hash
+    FROM sessions
+      JOIN users ON users.id = sessions.user_id
+    WHERE sessions.token_hash = $1;
   `, token_hash)
-	err := row.Scan(&user.ID)
-	if err != nil {
-		return nil, fmt.Errorf("user: %w", err)
-	}
-	row = ss.DB.QueryRow(`
-    SELECT email, password_hash
-    FROM users WHERE id = $1;
-  `, user.ID)
-	err = row.Scan(&user.Email, &user.PasswordHash)
+	err := row.Scan(&user.ID, &user.Email, &user.PasswordHash)
 	if err != nil {
 		return nil, fmt.Errorf("user: %w", err)
 	}
+
 	return &user, err
 }

models/sql/sessions.sql

@@ -1,5 +1,5 @@
 CREATE TABLE sessions (
   id SERIAL PRIMARY KEY,
-  user_id INT UNIQUE, 
+  user_id INT UNIQUE REFERENCES users (id) ON DELETE CASCADE,
   token_hash TEXT UNIQUE NOT NULL
 );