Question

We’re creating a historic archive for a world history database and we need a date lookup table which references all dates in AD. How to go about creating the values for this table – from 1AD to 2011 as YYYY/MM/DD? Database is MySQL.

Problems:

1. I’m using Excel to pre-populate the dates, then import into MySQL as: YYYY/MM/DD but Excel doesn’t recognize years like 0007, 0008, etc so I can’t auto-copy cells to generate dates. I have to manually do it and this will take days to go from 1AD to year 2011 as YYYY/MM/DD.

2. Leap years were introduced on 1752. If I programmatically generates dates how do I handle cases prior to 1752 with no leap years? It will generate wrong dates.

My table:

    CREATE TABLE `dates` (
      `date_id` int(10) NOT NULL,
      `format` char(10) NOT NULL,
      `century` int(10) NOT NULL,
      `decade` int(10) NOT NULL,
      `year` int(10) NOT NULL,
      `month` int(10) NOT NULL,
      `week` int(10) NOT NULL,
      `day` int(10) NOT NULL,
      `month_year` int(10) NOT NULL,
      `week_year` int(10) NOT NULL,
      `week_month` int(10) NOT NULL,
      `day_year` int(10) NOT NULL,
      `day_month` int(10) NOT NULL,
      `day_week` int(10) NOT NULL,
      PRIMARY KEY (`date_id`)
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Answer 1

Use something like this SQL (using my own table structure, not the one you had though):

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('1-01-01','2015-01-01');
OPTIMIZE TABLE time_dimension;