如何獲取SQL查詢：SHOW記錄通過量

Question

我想從一個表格式顯示銷售數量：

Sales    qty 
------------------------------------------ 
Sales > 50,000 500 
Sales < 2000  200 
Sales > 15,000 600 
------------------------------------------ 

如何創建呢？

我可以寫一個數量的查詢where > 50000但在這種情況下有三個50,000,2000,15,000，我怎麼能在結果中顯示所有這些？

Answer 1

一種方式來做到這一點是簡單地使用union all：

select 'Sales > 50,000' as sales, 
     count(*)   as qty 
     where sales > 50000 
union all 
select 'Sales < 2,000' as sales, 
     count(*)   as qty 
     where sales < 2000 
union all 
select 'Sales > 15,000' as sales, 
     count(*)   as qty 
     where sales > 15000 and sales <= 50000 

需要注意的是最後一個，我假設你希望它獨家從上述50,000（否則有60,000的sales顯示一排在這兩個部分）。

Answer 2

SELECT SUM(A), 
    SUM(B), 
    SUM(C) 
FROM 
    (SELECT 
    CASE 
     WHEN Sales > 50000 
     THEN 1 
     ELSE 0 
    END AS A, 
    CASE 
     WHEN Sales < 2000 
     THEN 1 
     ELSE 0 
    END AS B, 
    CASE 
     WHEN Sales > 15000 
     THEN 1 
     ELSE 0 
    END AS C 
    FROM table 
)