refactor : MySQL 문법 SNAKE_CASE로 변경 및 원본객체를 정렬할때는 동시성이슈를 피하기 위해 stream적용

src/main/java/com/flab/offcoupon/dto/response/MonthlyOrderStatistics.java

@@ -19,10 +19,10 @@ public final class MonthlyOrderStatistics {
     private final BigDecimal totalCouponPrice;
 
     public MonthlyOrderStatistics(MonthlyOrderStatisticsVo vo) {
-        this.yearMonth = (vo != null) ? vo.yearMonth() : null;
-        this.totalOrderCnt = (vo != null) ? vo.totalOrderCnt() : 0;
-        this.totalPaymentPrice = (vo != null) ? vo.totalPaymentPrice() : BigDecimal.ZERO;
-        this.totalCouponUseCnt = (vo != null) ? vo.totalCouponUseCnt() : 0;
-        this.totalCouponPrice = (vo != null) ? vo.totalCouponPrice() : BigDecimal.ZERO;
+        this.yearMonth = vo.yearMonth();
+        this.totalOrderCnt = vo.totalOrderCnt();
+        this.totalPaymentPrice = vo.totalPaymentPrice();
+        this.totalCouponUseCnt = vo.totalCouponUseCnt();
+        this.totalCouponPrice = vo.totalCouponPrice();
     }
 }

src/main/java/com/flab/offcoupon/service/StatisticsService.java

@@ -43,9 +43,10 @@ public ResponseDTO<List<MonthlyOrderStatistics>> getMonthlyOrderStatistics(Stati
         List<MonthlyOrderStatistics> monthlyStatisticsList = getMonthlyStatistics(startedAt, endedAt);
 
         // 월별로 정렬
-        monthlyStatisticsList.sort(Comparator.comparing(MonthlyOrderStatistics::getYearMonth));
-
-        return ResponseDTO.getSuccessResult(monthlyStatisticsList);
+        return ResponseDTO.getSuccessResult(monthlyStatisticsList
+                .stream()
+                .sorted(Comparator.comparing(MonthlyOrderStatistics::getYearMonth))
+                .toList());
     }
 
     /**
@@ -98,8 +99,9 @@ private List<MonthlyOrderStatistics> getMonthlyStatistics(LocalDate startedAt, L
 
     /**
      * 현재 월과 대상 날짜가 같은지 확인하는 메서드입니다.
+     *
      * @param currentYearMonth 현재 월
-     * @param target 대상 날짜
+     * @param target           대상 날짜
      * @return 현재 월과 대상 날짜가 같은지 여부
      */
     private boolean isSameYearMonth(YearMonth currentYearMonth, LocalDate target) {
@@ -109,8 +111,9 @@ private boolean isSameYearMonth(YearMonth currentYearMonth, LocalDate target) {
     /**
      * 시작일부터 종료일까지의 월 차이를 계산하는 메서드입니다.
      * 병렬 스트림에서 사용하기 위해 long 타입으로 반환합니다.
+     *
      * @param startedAt 시작일
-     * @param endedAt 종료일
+     * @param endedAt   종료일
      * @return 시작일부터 종료일까지의 월 차이
      */
     private long countMonthDifference(LocalDate startedAt, LocalDate endedAt) {

src/main/resources/mapper/StatisticsMapper.xml

@@ -5,15 +5,15 @@
 
 <mapper namespace="com.flab.offcoupon.repository.mysql.StatisticsRepository">
     <select id="getMonthlyOrderStatistics" parameterType="MonthlyStatisticsParameterVo" resultType="MonthlyOrderStatisticsVo">
-        select DATE_FORMAT(od.created_at,'%Y-%m') as YearMonth,
-            count(od.id) as totalOrderCnt,
-            SUM(od.total_payment_price) as totalPaymentPrice,
-            count(oc.id) as totalCouponUseCnt,
-            SUM(od.total_discount_price) as total_discount_price
+        select DATE_FORMAT(od.created_at,'%Y-%m') as `year_month`,
+            count(od.id) as total_order_cnt,
+            SUM(od.total_payment_price) as 'total_payment_price',
+            count(oc.id) as total_coupon_cnt,
+            SUM(od.total_discount_price) as 'total_discount_price'
         from order_detail od
             left join order_coupon oc on od.id = oc.order_id
         where od.created_at BETWEEN #{startedAt} and #{endedAt}
-        group by YearMonth
-        order by YearMonth;
+        group by `year_month`
+        order by `year_month`;
     </select>
 </mapper>