[#24] fix: sales log가 없을 때도 상품 목록 출력하도록 수정

be/kiosk/src/main/java/team/five/kiosk/repository/ProductRepository.java

@@ -20,14 +20,13 @@ public ProductRepository(final DataSource dataSource) {
     }
 
     public List<Product> findProductsBy(final String category) {
-        String sql = "SELECT p.*, SUM(sl.count) total_quantity"
-                + " FROM product p"
-                + " JOIN category c ON p.category_id = c.id"
-                + " JOIN sales_log sl ON p.id = sl.product_id"
-                + " WHERE c.name = :name"
-                + " AND DATE(sl.sales_at) = CURDATE()"
-                + " GROUP BY p.id"
-                + " ORDER BY total_quantity desc";
+        String sql = "SELECT p.*, SUM(sl.count) as total_quantity " +
+                "FROM product p " +
+                "         JOIN category c ON p.category_id = c.id " +
+                "         LEFT JOIN sales_log sl ON p.id = sl.product_id AND DATE(sl.sales_at) = CURDATE() " +
+                "WHERE c.name = :name " +
+                "GROUP BY p.id " +
+                "ORDER BY total_quantity desc";
 
         SqlParameterSource params = new MapSqlParameterSource("name", category);