如何在postgresql中获取频率

我有一张这样的表（表1）（我简化了它）

我想要一个如下的表格，我有每个季节的代码频率

  season  |  Number of Unique Codes  
----------+------------------------
   fall   |           2      
  winter  |           1           
  spring  |           1

到目前为止，我有：

SELECT 
    season, 
    count(DISTINCT code) AS "Number of Unique Codes"
FROM table_1
WHERE code IS NOT NULL
GROUP BY season
ORDER BY code desc;

---

但是，我遇到了一些问题。

您的错误出现在

ORDER BY

上，请将您的

ORDER BY

更改为按创建的别名排序

SELECT 
    season, 
    count(distinct code) AS "Number of Unique Codes"
FROM table_1
WHERE code IS NOT NULL
GROUP BY season
ORDER BY "Number of Unique Codes" DESC;

---

您的错误出现在

orderby

上，请将您的

orderby

更改为按创建的别名排序

SELECT 
    season, 
    count(distinct code) AS "Number of Unique Codes"
FROM table_1
WHERE code IS NOT NULL
GROUP BY season
ORDER BY "Number of Unique Codes" DESC;