fix hit ratio bug in app daily report

Author: githubname1024

cachecloud-web/src/main/resources/mapper/AppStatsDao.xml

@@ -321,9 +321,9 @@
         	max(connected_clients) as maxClientCount,
         	avg(command_count) as avgCommandCount, 
         	max(command_count) as maxCommandCount,
-            sum(hits)/sum(command_count) as avgHitRatio,
-	        max(hits/command_count) as maxHitRatio,
-	        min(hits/command_count) as minHitRatio,
+            sum(hits)/(sum(hits) + sum(misses)) as avgHitRatio,
+	        max(hits/(hits + misses)) as maxHitRatio,
+	        min(hits/(hits + misses)) as minHitRatio,
 	        avg(used_memory) as avgUsedMemory,
 	        max(used_memory) as maxUsedMemory,
 	        sum(expired_keys) as expiredKeys,