Question

我有一张这样的表：

year | revenue | organisation    
2010 | 83863   | asdf    
2011 | 5463    | asdf
2012 | 45345   | asdf
2009 | 32463   | ghjk
2010 | 352667  | ghjk

我需要搜索所有组织的最新收入，到目前为止，我可以构建一个像

这样的查询

Select new tablename(v.organisation, MAX(v.year), v.revenue) 
from tablename v 
where 1=1 group by v.name

但是我还需要另外一件事，那就是收入与上一年相比的变化百分比。

我怎么能做这两个功能？最好是在一个查询中？

由于

Answer 1

试试这个：

    let allViewController = self.storyboard!.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController;
    let favoritesViewController = self.storyboard!.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController;

子选择获得上一年的收入数字，然后执行以下公式：

func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
    let page = Int(scrollView.contentOffset.x / scrollView.frame.size.width)

    // how to send page to ContentViewController
    //delegate.pageChanged(page)
}

哪个应该给出百分比差异。我用你的假日期在我的环境中测试了它。

结果：

protocol PageChangedDelegate {
    func pageChanged(page: Int)
}

var delegate: PageChangedDelegate!

func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
    let page = Int(scrollView.contentOffset.x / scrollView.frame.size.width)

    delegate.pageChanged(page) // delegate is nil here
}

显示当前收入和上一年收入的结果：

SELECT v.organization,
       MAX(v.year) AS currentYear,
       v.revenue,
       ((v.revenue -
           (SELECT i.revenue
            FROM tablename i
            WHERE i.organization = v.organization
              AND i.year = MAX(v.year) - 1)) /
          (SELECT i.revenue
           FROM tablename i
           WHERE i.organization = v.organization
             AND i.year = MAX(v.year) - 1) * 100) AS percentDifference
FROM tablename v
WHERE 1 = 1
GROUP BY v.organization,
         v.year;

Answer 2

这是单程......

DROP TABLE IF EXISTS  my_table;

CREATE TABLE my_table
(year INT NOT NULL
,revenue INT NOT NULL
,organisation VARCHAR(12) NOT NULL
,PRIMARY KEY(year,organisation)
);

INSERT INTO my_table VALUES
(2010 ,83863   ,'asdf'),
(2011 ,5463    ,'asdf'),
(2012 ,45345   ,'asdf'),
(2009 ,32463   ,'ghjk'),
(2010 ,352667  ,'ghjk');

SELECT x.*
      , ((x.revenue - z.revenue)/z.revenue) * 100 pct_diff
   FROM my_table x
   JOIN
      ( SELECT organisation
             , MAX(year) max_year 
          FROM my_table 
         GROUP 
            BY organisation
      ) y
     ON y.organisation = x.organisation 
    AND y.max_year = x.year
   LEFT
   JOIN my_table z
     ON z.organisation = x.organisation
    AND z.year = x.year - 1;

+------+---------+--------------+----------+
| year | revenue | organisation | pct_diff |
+------+---------+--------------+----------+
| 2010 |  352667 | ghjk         | 986.3660 |
| 2012 |   45345 | asdf         | 730.0384 |
+------+---------+--------------+----------+

这是运行历史的一个（慢）版本......

 SELECT x.*
      , ((x.revenue - y.revenue)/y.revenue) * 100 pct_diff
   FROM my_table x
   LEFT
   JOIN my_table y
     ON y.organisation = x.organisation
    AND y.year = x.year - 1
  ORDER 
     BY organisation
      , year;

......如果花一点时间（/记得如何），我会发布更快的替代方案

MySQL：如何获得一个字段与前一个字段相比的变化百分比

2 个答案: