fix：修改了聚合查询

internal/dao/sensor.go

@@ -44,42 +44,47 @@ func (dao *SensorDAO) Insert(data *model.SensorData) error {
 func (dao *SensorDAO) GetAggregatedData(start, end time.Time, interval string) ([]model.AggregatedData, error) {
 	// 参数化时间间隔
 	var intervalMinutes int
-	var timeFormat string
 
 	switch interval {
 	case "5min":
 		intervalMinutes = 5
-		timeFormat = "%Y-%m-%dT%H:%i:00"
 	case "30min":
 		intervalMinutes = 30
-		timeFormat = "%Y-%m-%dT%H:%i:00"
 	default: // 1hour
 		intervalMinutes = 60
-		timeFormat = "%Y-%m-%dT%H:00:00"
 	}
 
-	// 计算秒数
-	intervalSeconds := intervalMinutes * 60
-
-	// 构建通用查询
+	// 使用子查询和时间桶来实现聚合
 	query := `
+		WITH time_buckets AS (
 			SELECT 
-			DATE_FORMAT(MIN(timestamp), '%Y-%m-%dT%H:%i:%S') as ts,
-			ROUND(AVG(temperature)/10, 1) as avg_temp,
-			MAX(rainfall) - MIN(rainfall) as rainfall,
-			ROUND(AVG(humidity)/10, 1) as avg_humidity,
-			ROUND(AVG(wind_speed)/10, 1) as avg_wind_speed
+				DATE_FORMAT(
+					DATE_SUB(timestamp, INTERVAL MOD(MINUTE(timestamp), ?) MINUTE), 
+					'%Y-%m-%dT%H:%i:00'
+				) AS bucket_time,
+				AVG(temperature) AS temp,
+				MAX(rainfall) - MIN(rainfall) AS rain,
+				AVG(humidity) AS hum,
+				AVG(wind_speed) AS wind
 			FROM sensor_data
 			WHERE timestamp BETWEEN ? AND ?
-		GROUP BY FLOOR(UNIX_TIMESTAMP(timestamp)/?)
-		ORDER BY ts DESC
+			GROUP BY bucket_time
+		)
+		SELECT 
+			bucket_time, 
+			ROUND(temp/10, 1) AS avg_temp,
+			rain AS rainfall,
+			ROUND(hum/10, 1) AS avg_humidity,
+			ROUND(wind/10, 1) AS avg_wind_speed
+		FROM time_buckets
+		ORDER BY bucket_time DESC
 	`
 
 	// 执行查询
 	rows, err := dao.db.Query(
 		query,
-		start, end, // 时间范围
-		intervalSeconds, // GROUP BY参数
+		intervalMinutes, // 时间桶参数
+		start, end       // 时间范围
 	)
 
 	if err != nil {