MySql查詢上周（周一到周日）每天的日期！土方！

首先介紹一個函數：YEARWEEK(date[,mode])

主要說明一下后面的可選參數mode，這個參數就是指定一周里面哪一天是第一天。

默認一周是從周日開始，這顯然不太符合我們的要求。要指定每周從周一開始的話，mode=1就好了。

下圖為該參數的說明：

 

 

接下來進入正題，直接上SQL吧

SELECT 
    date_format(lastWeek.`timeDay`,'%Y-%m-%d') as 'timeDay' 
FROM (
    select DATE_SUB(NOW(),interval 13 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 12 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 11 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 10 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 9 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 8 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 7 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 6 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 5 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 4 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 3 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 2 day) as 'timeDay'
    UNION ALL 
    select DATE_SUB(NOW(),interval 1 day) as 'timeDay'
) as lastWeek 
WHERE YEARWEEK(lastWeek.`timeDay`,1) = YEARWEEK(NOW(),1)-1

 

為什么說這是個土方呢，哈哈！首先看上去莫名的土，理解一下邏輯如下：

假如今天是周一，我要得出上周一和上周日的日期，很簡單：
上周一距離今天7天=select DATE_SUB(NOW(),interval 7 day);
上周日距離今天1天=select DATE_SUB(NOW(),interval 1 day);

沒毛病，那如果今天是周日呢？
上周一距離今天13天=select DATE_SUB(NOW(),interval 13 day);
上周日距離今天7天=select DATE_SUB(NOW(),interval 7 day);

沒錯，這里就是查詢出來上周所有可能的日期，因為這個問題的難點就是
我們不能指定當前的日期。

查詢出來之后在結合MySql的函數YEARWEEK，就可以得出上周的日期了

 

我寫這個的SQL的原因，是因為有這么個需求：要統計上周每天的注冊人數，以柱狀圖的形式展現。

要是直接使用

SELECT 
    DATE_FORMAT(regist_date,'%Y-%m-%d') '注冊時間',COUNT(*) as '注冊人數' 
FROM t_user 
WHERE YEARWEEK(regist_date,1) = YEARWEEK(NOW(),1)-1
GROUP BY DATE_FORMAT(regist_date,'%Y-%m-%d')

會出現如果有一天沒有注冊人數的話，這一天就沒有數據，產品的需求呢是沒有注冊人數的話顯示為0。

於是就有了下面的寫法

SELECT 
    t1.timeDay as '日期',t2.`注冊人數`
FROM (
    SELECT 
        date_format(lastWeek.`timeDay`,'%Y-%m-%d') as 'timeDay' 
    FROM (
        select DATE_SUB(NOW(),interval 13 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 12 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 11 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 10 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 9 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 8 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 7 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 6 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 5 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 4 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 3 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 2 day) as 'timeDay'
        UNION ALL 
        select DATE_SUB(NOW(),interval 1 day) as 'timeDay'
    ) as lastWeek 
    WHERE YEARWEEK(lastWeek.`timeDay`,1) = YEARWEEK(NOW(),1)-1
) as t1
LEFT JOIN (
    SELECT 
        DATE_FORMAT(regist_date,'%Y-%m-%d') '注冊時間',COUNT(*) as '注冊人數' 
    FROM t_user 
    WHERE YEARWEEK(regist_date,1) = YEARWEEK(NOW(),1)-1
    GROUP BY DATE_FORMAT(regist_date,'%Y-%m-%d')
) as t2 ON t1.timeDay = t2.`注冊時間`
ORDER BY t1.timeDay

這樣就搞定了。你還可以以這種方法查出上個月的日期哦。

希望能幫到你~