新增删除缓存操作。(大于7天的数据删除)

application/third_party/train/models/BIZ_train_model.php

@@ -47,7 +47,8 @@ class BIZ_train_model extends CI_Model {
         return $query;				
 	}
 	
-	//获取价格
+	//获取缓存的火车信息
+	//如果读取到缓存是7天以前的数据就不返回任何数据，并且将其删除。
 	public function get_train_info($tpc_from_station,$tpc_to_station){
 		$sql = "SELECT 
 					* 
@@ -57,10 +58,28 @@ class BIZ_train_model extends CI_Model {
 					tpc_from_station = '$tpc_from_station'
 				AND	
 					tpc_to_station = '$tpc_to_station'";
-		$query = $this->INFO->query($sql);		
-		return $query->row();
+		$query = $this->INFO->query($sql);
+		$cache_time = strtotime($query->row()->tpc_datetime);
+		$now_time = time();
+		$differ_time = ($now_time - $cache_time) / 86400;
+		if($differ_time >= 7){
+			$this->delete_traincache($tpc_from_station,$tpc_to_station);
+			return null;
+		}else{
+			return $query->row();
+		}
 	}
 	
+	//删除缓存操作
+	function delete_traincache($tpc_from_station,$tpc_to_station){
+		$sql = "DELETE FROM 
+					TrainPriceCache 
+				WHERE 
+					tpc_from_station = '$tpc_from_station' 
+				AND 
+					tpc_to_station = '$tpc_to_station'";
+		$query = $this->INFO->query($sql);
+	}
 	
     function biz_order_detail($cold_sn) {
         $sql = "