Question

我有这两个表：

var areaCalc = function(x,y) {
    this.x = x ;
    this.y = y ;
} 
areaCalc .prototype = {
        area: function() { return (this.x * this.y); }
}
//var newarea = new areaCalc (5,23);

function onObjectWithPrototype () {
     areaCalc(2,3);
     alert(areaCalc.prototype.area());
     //alert(newarea .area());
 }

和：

customer
  id
  name
  created_at

我想获得action id customer_id type created_at和customer.created_at之间的平均时间差，其中action.created_at和操作是第一个条目（操作可能有很多action.type = "call0"）

现在，我有这个查询：

type = "call0"

不知道为什么，此查询返回几行-每行用于输入操作。

如何返回整个平均值计算？

Answer 1

如果您希望获得总结果，则不要按customer.id分组

  SELECT AVG(TIME_TO_SEC(timediff(action.created_at, customer.created_at)) / 60) AS diff
    FROM action
    JOIN customer ON action.customer_id = customer.id
    WHERE action.type = "call0"

否则，如果您要为每个customer.id求平均值，请尝试同时显示相应的customer.id

SELECT customer.id, AVG(TIME_TO_SEC(timediff(action.created_at, customer.created_at)) /60) AS diff
  FROM action
 JOIN customer ON action.customer_id = customer.id
  WHERE action.type = "call0"
  GROUP BY customer.id
  ORDER BY action.created_at ASC

MySQL-获取2个表之间的平均时间差异

1 个答案: