current duplicate check uses IS ? which is fragile in MySQL. Using the NULL-safe equality operator <=> instead.

internal/storage/tickets/create.go

@@ -7,7 +7,6 @@ import (
 	"synlotto-website/internal/models"
 )
 
-// ToDo: Has both insert and select need to break into read and write.
 func InsertTicket(db *sql.DB, ticket models.Ticket) error {
 	var bonus1Val interface{}
 	var bonus2Val interface{}
@@ -24,14 +23,18 @@ func InsertTicket(db *sql.DB, ticket models.Ticket) error {
 		bonus2Val = nil
 	}
 
-	query := `
+	// Use NULL-safe equality <=> for possible NULLs
+	const dupQuery = `
 		SELECT COUNT(*) FROM my_tickets
-	WHERE game_type = ? AND draw_date = ?
+		WHERE game_type = ?
+		  AND draw_date = ?
 		  AND ball1 = ? AND ball2 = ? AND ball3 = ?
-	  AND ball4 = ? AND ball5 = ? AND bonus1 IS ? AND bonus2 IS ?;`
+		  AND ball4 = ? AND ball5 = ?
+		  AND bonus1 <=> ? AND bonus2 <=> ?;
+	`
 
 	var count int
-	err := db.QueryRow(query,
+	if err := db.QueryRow(dupQuery,
 		ticket.GameType,
 		ticket.DrawDate,
 		ticket.Ball1,
@@ -41,30 +44,30 @@ func InsertTicket(db *sql.DB, ticket models.Ticket) error {
 		ticket.Ball5,
 		bonus1Val,
 		bonus2Val,
-	).Scan(&count)
+	).Scan(&count); err != nil {
-
+		return err
+	}
 	isDuplicate := count > 0
 
-	insert := `
+	const insert = `
 		INSERT INTO my_tickets (
 			game_type, draw_date,
 			ball1, ball2, ball3, ball4, ball5,
 			bonus1, bonus2, duplicate
-	) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?);`
+		) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?);
+	`
 
-	_, err = db.Exec(insert,
+	_, err := db.Exec(insert,
 		ticket.GameType, ticket.DrawDate,
 		ticket.Ball1, ticket.Ball2, ticket.Ball3,
 		ticket.Ball4, ticket.Ball5,
 		bonus1Val, bonus2Val,
 		isDuplicate,
 	)
-
 	if err != nil {
 		log.Println("❌ Failed to insert ticket:", err)
 	} else if isDuplicate {
 		log.Println("⚠️ Duplicate ticket detected and flagged.")
 	}
-
 	return err
 }