MySQL中按日期分組的年份字段

Question

我有一個帶有客戶表的MySQL數據庫。 一些偽數據是：

customer_id    date
000001         2008-10-10
000002         2008-11-11
000003         2010-01-02
000004         2007-04-03
000005         2010-05-05

我想運行一個查詢，它會給我這樣的結果：

year    customer_count
2007    1
2008    2
2010    2

我知道我需要使用分組依據，但是我無法解決如何根據日期字段的年值進行分組以及如何按順序進行分組的問題。

Answer 1

從日期中提取年份並按其分組

select year(date) as year, 
       count(customer_id) as customers
from your_table
group by year
order by year asc

Answer 2

使用YEAR函數獲取日期的年份部分，並將其用於分組和排序。

SELECT YEAR(date) AS year, COUNT(*) AS customer_count
FROM customer
GROUP BY year
ORDER BY year

Answer 3

使用EXTRACT函數獲取日期的相關部分：

select extract(YEAR from join_d)"Year",count(DISTINCT customer_id) "customer_count" 
from  customer 
group by year
order by year;