如何在SQL中有三个字段的Pivot？

Question

我有一个名为product的表，想要执行数据透视操作并查找以下结果：

OutPut要求：

如何在具有三个字段的SQL中进行Pivot？

Answer 1

var Obj = function() {
   this.property = 1;
   this.arr = [...] // array containing elements we want to add event listeners to
   for (...) {
      this.arr[i].addEventListener("click", this.listener, false);
   }
}

Obj.prototype.listener = function() {
   console.log( this.property ); // DOES NOT WORK! *this* does not point to Obj.
}
var a = new Obj();