mysqlの2つの日付の間の土曜日と日曜日の総数を計算する方法

開始日から終了日までのすべての日付（両端を含む）を含むテーブルがない場合は、最初に指定された日付範囲（両端を含む）の間のすべての日付を作成するクエリを採用する必要があります。次に、WEEKDAYを使用します MySQLの機能 その日がSaturdayであるかどうかを確認します またはSunday

SELECT 
dateTable.Day,
DAYNAME(dateTable.Day) AS dayName
FROM 
(   SELECT ADDDATE('2016-07-01', INTERVAL @i:[email protected]+1 DAY) AS DAY
    FROM (
        SELECT a.a
        FROM (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS a
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS b
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS c
    ) a
    JOIN (SELECT @i := -1) r1
    WHERE 
    @i < DATEDIFF('2016-08-01', '2016-07-01')

) AS dateTable
WHERE WEEKDAY(dateTable.Day) IN (5,6)
ORDER BY dateTable.Day;

WORKING DEMO

注： WEEKDAY 日付の平日インデックスを返します（0 =月曜日、1 =火曜日、…6 =日曜日）。

編集：

countだけが必要な場合 ：

SELECT 
COUNT(*) AS total
FROM 
(   SELECT ADDDATE('2016-07-01', INTERVAL @i:[email protected]+1 DAY) AS DAY
    FROM (
        SELECT a.a
        FROM (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS a
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS b
        CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS c
    ) a
    JOIN (SELECT @i := -1) r1
    WHERE 
    @i < DATEDIFF('2016-08-01', '2016-07-01')

) AS dateTable
WHERE WEEKDAY(dateTable.Day) IN (5,6)

デモ