mysql：計算每個組中的值的數量

Question

我有一個問題：

SELECT 
    count(session_id_open) as opens,
    count(session_id_visit) as visits,
    date_intervals_open,
    group_concat(date_intervals_visit)
FROM
    bla
GROUP BY date_intervals_open

我得到了下表。 我需要的是找出group_concat中出現的每個值出現的百分比。 所以，基本上，我需要計算每個組中的值的數量（date_intervals_visit）（data_intervals_open）

opens   visits  date_intervals_open group_concat        
213    5        day (12-16)             evening (17-21),evening (17-21),day (12-16),day (12-16),day (12-16)
113    0        evening (17-21)         NULL
11     0        late evening (22-00)    NULL
396    12       morning (5-11)          morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11),morning (5-11)
9      0        night (1-4)              NULL

這大約是我需要獲得的表格。 在第一個記錄的晚上有40，因為“晚上（17-21）”出現兩次，所有出現的次數是5. 2/5 * 100 = 40

opens   visits  date_intervals_open evening(17-21)  day(12-16)  morning (5-11)  
213    5        day (12-16)             40          60        0
113    0        evening (17-21)         NULL        NULL      NULL
11     0        late evening (22-00)    NULL        NULL     NULL
396    12       morning (5-11)          0        0     100
9      0        night (1-4)             NULL

PS：我使用group_concat只是想象我在那里的價值。 我不必使用它，因為之后解析它將是一個額外的努力。

Answer 1

你基本上需要一個樞軸，進行一些進一步的計算。 我的答案的基礎來自以下關於MySQL中的轉軸記錄的優秀SO主題。 我假設你有一個固定數量的date_intervals_visit值，因為這些值似乎涵蓋了整天，因此我使用具有固定計數的條件計數方法。 我將在示例代碼中添加2個類別，您可以將其擴展為涵蓋所有date_intervals_visit值。

SELECT 
    count(session_id_open) as opens,
    count(session_id_visit) as visits,
    date_intervals_open,
    round(sum(if(date_intervals_visit='morning (5-11)',1,0)) / count(session_id_visit) * 100,2) as `morning (5-11)`,
    round(sum(if(date_intervals_visit='day (12-16)',1,0)) / count(session_id_visit) * 100,2) as `day (12-16)`
FROM
    bla
GROUP BY date_intervals_open

如果date_intervals_open值可能有0次訪問，那么您需要在表達式中檢查0：

if(count(session_id_visit)=0, 0, <above formula>)

Answer 2

SELECT 
    count(session_id_open) as opens,
    @visits := count(session_id_visit) as visits,
    date_intervals_open,
    ROUND(100 * SUM(date_intervals_visit = 'evening(17-21)') / @visits) AS 'evening(17-21)',
    ROUND(100 * SUM(date_intervals_visit = 'day (12-16)') / @visits) AS 'day (12-16)',
    ROUND(100 * SUM(date_intervals_visit = 'morning (5-11)') / @visits)'morning (5-11)',
FROM
    bla
GROUP BY date_intervals_open

Answer 3

使用這樣的函數：

CREATE FUNCTION [dbo].[fn_SplitString](
    @InputStr   varchar(Max),
    @Seperator  varchar(10))
RETURNS @OutStrings TABLE (ItemNo int identity(1,1), Item varchar(256))

AS
BEGIN

    DECLARE @Str varchar(2000),
            @Poz int, @cnt int

    --DECLARE @OutStrings TABLE (Item varchar(2000))

    SELECT @Poz = CHARINDEX (@Seperator, @InputStr), @cnt = 0
    WHILE @Poz > 0 AND @cnt <= 10000
    BEGIN
        SELECT @Str = SubString(@InputStr, 1, @Poz - 1)
        INSERT INTO @OutStrings(Item) VALUES(@Str)

        SELECT @InputStr = Right(@Inputstr, Len(@InputStr) - (len(@Str) + len(@Seperator)))
        SELECT @Poz = CHARINDEX (@Seperator, @InputStr), @cnt = @cnt + 1
    END
    IF @InputStr <> ''
    BEGIN
        INSERT INTO @OutStrings(Item) VALUES(@InputStr)
    END

    RETURN
END

通過以下方式：

SELECT  opens,
        visits,
        date_intervals_open,
        [evening(17-21)]/[All]*100 AS [evening(17-21)],
        [day(12-16)]/[All]*100 AS [day(12-16)],
        [morning (5-11)]/[All]*100 AS [morning (5-11)]
FROM
    (   
    SELECT 
        count(session_id_open) as opens,
        count(session_id_visit) as visits,
        date_intervals_open,
        (SELECT COUNT(Item) FROM [dbo].[fn_SplitString](LTRIM(RTRIM(group_concat(date_intervals_visit))), ',') WHERE item  = 'evening(17-21)') AS [evening(17-21)],
        (SELECT COUNT(Item) FROM [dbo].[fn_SplitString](LTRIM(RTRIM(group_concat(date_intervals_visit))), ',') WHERE item = 'day(12-16)') AS [day(12-16)],
        (SELECT COUNT(Item) FROM [dbo].[fn_SplitString](LTRIM(RTRIM(group_concat(date_intervals_visit))), ',') WHERE item = 'morning (5-11)') AS [morning (5-11)],
        (SELECT COUNT(Item) FROM [dbo].[fn_SplitString](LTRIM(RTRIM(group_concat(date_intervals_visit))), ',')) AS [All]
    FROM
        bla
    GROUP BY date_intervals_open
    )blabla