在没有子查询的情况下在 mysql 中获取比率答案

【问题标题】：Getting ratios in mysql without subqueries在没有子查询的情况下在 mysql 中获取比率
【发布时间】：2020-03-13 21:39:09
【问题描述】：

我想从下表中运行一个查询，得到从执行办公室支付的金额与应付总金额的比率：

 CREATE TABLE  offices (
   name VARCHAR(255),
   ID VARCHAR(255),
  level VARCHAR(255)
 );



 INSERT INTO offices (name,ID,level)
   VALUES 
  ('chairman', 'ad1', 'admin'),
  ('MD', 'ad2', 'admin'),
  ('CEO', 'ad3', 'admin'),
  ('president', 'ex1', 'exec' ),
  ('VP', 'ex2', 'exec'),
  ('GM', 'ex3', 'exec'),
  ('HOD', 'ex4', 'exec');

CREATE TABLE  cheques (
  payee VARCHAR(255) ,
 officeID VARCHAR(255),
 amount INT(),
 status VARCHAR(255) 
 );


INSERT INTO cheques
 VALUES ('john', 'ad2', '100',  'paid'),
 ('john',   'ad3',  '50',   'owed'),
 ('john',   'ex3',  '80',   'paid'),
 ('john',   'ex4',  '150',  'owed'),
 ('john',   'ex1',  '35',   'paid'),
('mary',    'ad1',  '200',  'paid'),
('mary',    'ad3',  '90',   'owed'),
('mary',    'ex2',  '110',  'paid'),
('mary',    'ex4',  '40',   'owed'),
('mary',    'ex1',  '60',   'paid'),
('jane',    'ad1',  '75',   'paid'),
('jane',    'ad3',  '120',  'paid');

预期结果如下：

data.frame(
 payee=c("john","mary"),
 totalpaid=c(115,170),
 status=c("paid", "paid"),
 totalsdue = c(415, 500),
 ratio=(0.28, 0.34)
   )

我已经能够从以下执行办公室获得总薪水

  SELECT c.payee, SUM(c.amount) as totalpaid, c.status
   FROM cheques c
   JOIN offices o
   ON c.officeID = o.ID
  WHERE 
   o.level LIKE '%ex%'
 AND 
   c.status LIKE '%paid%'
 GROUP BY payee

总欠款如下

   SELECT  c.payee, SUM(c.amount) as totalsdue
     FROM cheques c
      GROUP BY payee

我尝试过的没有成功：

  SELECT  
   c.payee, SUM(c.amount) as totalsdue
      totalsdue/totalpaid as ratio
      FROM cheques c
      WHERE c.payee IN
        (SELECT c.payee, SUM(c.amount) as totalpaid, c.status
           FROM cheques c
           JOIN offices o
           ON c.officeID = o.ID
           WHERE 
             o.level LIKE '%ex%'
           AND 
             c.status LIKE '%paid%'
          GROUP BY payee )
      GROUP BY payee

如何通过单个查询获得预期结果。

【问题讨论】：

为什么子查询可能很慢？
在研究我的问题时，我遇到了这个在某处提到的线程：stackoverflow.com/questions/14383100/…

标签： mysql sql

【解决方案1】：

对于结果，您可以使用 JOIN 中的子查询

  SELECT t1.payee, t1.totalsdue, t1.totalsdue/t2.totalpaid 
  from  (
      SELECT  c.payee, SUM(c.amount) as totalsdue
      FROM cheques c
      GROUP BY payee
  ) t1
  INNER JOIN  (
    SELECT c.payee, SUM(c.amount) as totalpaid, c.status
    FROM cheques c
    JOIN offices o  ON c.officeID = o.ID
    WHERE o.level LIKE '%ex%'
    AND   c.status LIKE '%paid%'
    GROUP BY payee 
 ) t2 on t1.payee = t2.payee

为了更好的性能..
检查你是否真的需要 like 和 wildchar 匹配，或者你可以得到完全匹配的查询

并确保您对可能参与连接的列和位置有适当的索引

表格检查列（officeID，payee）

或者如果列状态允许精确匹配列（officeID、status、payee）

【讨论】：

【解决方案2】：

我想从下表中运行一个查询，得到从执行办公室支付的金额与应付总金额的比率。

我认为你只需要窗口函数：

SELECT c.payee, SUM(c.amount) as totalsdue,
       SUM(c.amount) / SUM(SUM(c.amount)) OVER () as ratio
FROM cheques c
GROUP BY payee;

您的查询中有其他条件，但问题中没有说明。

【讨论】：