Question

我们说我有一张没有数据的表。该表格包含entry_date列。我将提供两个日期，如"2017-06-14","2017-06-18"。我想为每个日期选择存在的行数，如

    count | entry_date
    ------------
    0     | 2017-06-14
    0     | 2017-06-15
    0     | 2017-06-16
    0     | 2017-06-17
    0     | 2017-06-18

*表可能没有特定日期的条目，因此它应该在该日期返回0

Answer 1

如下面的代码所示。您可以创建日历表。我们根据需要为我们提供准确的日历。进入该日历表。

DROP TABLE IF EXISTS time_dimension;

CREATE TABLE time_dimension (
        id                      INTEGER PRIMARY KEY,  -- year*10000+month*100+day
        db_date                 DATE NOT NULL,
        year                    INTEGER NOT NULL,
        month                   INTEGER NOT NULL, -- 1 to 12
        day                     INTEGER NOT NULL, -- 1 to 31
        quarter                 INTEGER NOT NULL, -- 1 to 4
        week                    INTEGER NOT NULL, -- 1 to 52/53
        day_name                VARCHAR(9) NOT NULL, -- 'Monday', 'Tuesday'...
        month_name              VARCHAR(9) NOT NULL, -- 'January', 'February'...
        holiday_flag            CHAR(1) DEFAULT 'f' CHECK (holiday_flag in ('t', 'f')),
        weekend_flag            CHAR(1) DEFAULT 'f' CHECK (weekday_flag in ('t', 'f')),
        event                   VARCHAR(50),
        UNIQUE td_ymd_idx (year,month,day),
        UNIQUE td_dbdate_idx (db_date)

) Engine=MyISAM;

DROP PROCEDURE IF EXISTS fill_date_dimension;
DELIMITER //
CREATE PROCEDURE fill_date_dimension(IN startdate DATE,IN stopdate DATE)
BEGIN
    DECLARE currentdate DATE;
    SET currentdate = startdate;
    WHILE currentdate < stopdate DO
        INSERT INTO time_dimension VALUES (
                        YEAR(currentdate)*10000+MONTH(currentdate)*100 + DAY(currentdate),
                        currentdate,
                        YEAR(currentdate),
                        MONTH(currentdate),
                        DAY(currentdate),
                        QUARTER(currentdate),
                        WEEKOFYEAR(currentdate),
                        DATE_FORMAT(currentdate,'%W'),
                        DATE_FORMAT(currentdate,'%M'),
                        'f',
                        CASE DAYOFWEEK(currentdate) WHEN 1 THEN 't' WHEN 7 then 't' ELSE 'f' END,
                        NULL);
        SET currentdate = ADDDATE(currentdate,INTERVAL 1 DAY);
    END WHILE;
END
//
DELIMITER ;

TRUNCATE TABLE time_dimension;

CALL fill_date_dimension('2000-01-01','2018-01-01');

创建该日历表后，您可以在下面写下查询，它将解决您的问题。

SELECT COUNT(datetime) ,DB_DATE FROM time_dimension TD
LEFT JOIN YOUR_TABLENAME TN ON DATE(TN.entry_date)=TD.db_date
WHERE TD.DB_DATE BETWEEN '2017-06-14' AND '2017-06-18'
GROUP BY  DATE(DB_DATE);

希望这会有所帮助。

MySQL没有行的两个日期之间的每个日期的行数

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