Mysql 计算多个 SUM() 变量

Question

我想计算 2 sum() 我试过如下查询，但速度很慢。有什么改进的想法吗？

SELECT customer, 
       SUM(CASE WHEN book_day BETWEEN '2020-01-01' AND '2020-01-31'  
                THEN pax+free 
                ELSE 0 
                END) AS January,
       SUM(CASE WHEN book_day BETWEEN '2020-02-01' AND '2020-02-31'  
                THEN pax+free 
                ELSE 0 
                END) AS February,
       ( SUM(CASE WHEN book_day BETWEEN '2020-01-01' AND '2020-01-31'  
                  THEN pax+free 
                  ELSE 0 
                  END) + 
         SUM(CASE WHEN book_day BETWEEN '2020-02-01' AND '2020-02-31'  
                  THEN pax+free 
                  ELSE 0 
                  END) ) AS total
 FROM rezervations

我怎样才能像January + February as total

那样更简单

Answer 1

在 where 子句中保留 BETWEEN '2020-01-01' AND '2020-02-29'。

确保 book_day 列上有索引

SELECT customer, 
SUM(CASE WHEN book_day BETWEEN '2020-01-01' AND '2020-01-31' THEN pax+free ELSE 0 END) as January,
SUM(CASE WHEN book_day BETWEEN '2020-02-01' AND '2020-02-29'  THEN pax+free ELSE 0 END) as February,
(SUM(CASE WHEN book_day BETWEEN '2020-01-01' AND '2020-02-29'  THEN pax+free ELSE 0 END) ) as total
 FROM rezervations 
WHERE
book_day BETWEEN '2020-01-01' AND '2020-02-29'

Mysql 计算多个 SUM() 变量

Mysql calculate multiple SUM() varialbe

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