#31 - 문제 3 sum(), group by() 로 변경하기

주어진 문제 구하는 방식을 쿼리를 중심으로 구하도록 변경했다. `sum(), group by()` 쿼리문을 사용하여 요구사항 이외의 다른 문법을 배제하고 코드가 더욱 간결하고 적절하게 쿼리가 수행됐다.

library-app/src/main/java/com/group/libarayapp/controller/task04/Task04ExController.java

@@ -38,38 +38,25 @@ public void salesQuantityFruit(@RequestBody Task04ExRequest request) {
         jdbcTemplate.update(sql, request.getSalesQuantity() + 1, request.getId());
     }
 
-    private final List<Task04CreateRequest> Task04CreateRequestList = new ArrayList<>();
-    long salesSum = 0;
-    long notSalesSum = 0;
-
     // 문제 3 - sum, group by 미적용
     @GetMapping("/api/v1/fruit/stat")
     public Task04ExResponse SalesAmountFruit(@RequestParam String name) {
-
-        // 모든 값을 List 에 저장
-        String readSql = "select * from fruit";
-        jdbcTemplate.query(readSql, (rs, rowNum) -> {
-            Task04CreateRequest createRequest = new Task04CreateRequest(
-                    rs.getLong("id"),
-                    rs.getString("name"),
-                    rs.getDate("warehousing").toLocalDate(),
-                    rs.getLong("price"),
-                    rs.getInt("salesQuantity"));
-            Task04CreateRequestList.add(createRequest);
-
-            return createRequest;
-        });
-
-        // 판매된 상품과 판매되지 않은 상품의 가격을 반환
-        for (Task04CreateRequest task04CreateRequest : Task04CreateRequestList) {
-            if (task04CreateRequest.getName().equals(name)) {
-                if (task04CreateRequest.getSalesQuantity() > 0) {
-                    salesSum += task04CreateRequest.getSalesQuantity() * task04CreateRequest.getPrice();
-                } else {
-                    notSalesSum += task04CreateRequest.getPrice();
-                }
-            }
-        }
-        return new Task04ExResponse(salesSum, notSalesSum);
+        String readNotSalesSql = """
+                select sum(price) as notSalesAmount
+                from fruit
+                where name=? and salesQuantity = 0
+                group by salesQuantity;
+                """;
+        List<Integer> readNotSalesList = jdbcTemplate.query(readNotSalesSql, (rs, rowNum) -> rs.getInt("notSalesAmount"), name);
+
+        String readSalesSql = """
+                select sum(price) as salesAmount
+                from fruit
+                where name=? and salesQuantity = 1
+                group by salesQuantity;
+                """;
+        List<Integer> readSalesList = jdbcTemplate.query(readSalesSql, (rs, rowNum) -> rs.getInt("salesAmount"), name);
+
+        return new Task04ExResponse(readSalesList, readNotSalesList);
     }
-}
+}

library-app/src/main/java/com/group/libarayapp/dto/task04/response/Task04ExResponse.java

@@ -1,12 +1,14 @@
 package com.group.libarayapp.dto.task04.response;
 
+import java.util.List;
+
 public class Task04ExResponse {
-    private long salesAmount;
-    private long notSalesAmount;
+    private final long salesAmount;
+    private final long notSalesAmount;
 
-    public Task04ExResponse(long salesAmount, long notSalesAmount) {
-        this.salesAmount = salesAmount;
-        this.notSalesAmount = notSalesAmount;
+    public Task04ExResponse(List<Integer> readSalesList, List<Integer> readNotSalesList) {
+        this.salesAmount = readSalesList.get(0);
+        this.notSalesAmount = readNotSalesList.get(0);
     }
 
     public long getSalesAmount() {