Beispielanalyse des Prinzips und der Lösung des MySQL-Gleitreihenfolgeproblems

CREATE TABLE MonatlicheBestellungen(
Bestellmonat DATUM,
Bestellnummer INT UNSIGNED,
PRIMÄRSCHLÜSSEL (Bestellmonat)
);

INSERT INTO MonthlyOrders SELECT '2010-02-01',23;
INSERT INTO MonthlyOrders SELECT '2010-03-01',26;
INSERT INTO MonthlyOrders SELECT '2010-04-01',24;
INSERT INTO MonthlyOrders SELECT '2010-05-01',27;
INSERT INTO MonthlyOrders SELECT '2010-06-01',26;
INSERT INTO MonthlyOrders SELECT '2010-07-01',32;
INSERT INTO MonthlyOrders SELECT '2010-08-01',34;
INSERT INTO MonthlyOrders SELECT '2010-09-01',30;
INSERT INTO MonthlyOrders SELECT '2010-10-01',31;
INSERT INTO MonthlyOrders SELECT '2010-11-01',32;
INSERT INTO MonthlyOrders SELECT '2010-12-01',33;
INSERT INTO MonthlyOrders SELECT '2011-01-01',31;
INSERT INTO MonthlyOrders SELECT '2011-02-01',34;
INSERT INTO MonthlyOrders SELECT '2011-03-01',34;
INSERT INTO MonthlyOrders SELECT '2011-04-01',38;
INSERT INTO MonthlyOrders SELECT '2011-05-01',39;
INSERT INTO MonthlyOrders SELECT '2011-06-01',35;
INSERT INTO MonthlyOrders SELECT '2011-07-01',49;
INSERT INTO MonthlyOrders SELECT '2011-08-01',56;
INSERT INTO MonthlyOrders SELECT '2011-09-01',55;
INSERT INTO MonthlyOrders SELECT '2011-10-01',74;
INSERT INTO MonthlyOrders SELECT '2011-11-01',75;
INSERT INTO MonthlyOrders SELECT '2011-12-01',14;

WÄHLEN
  DATE_FORMAT(a.Bestellmonat, '%Y%m') AS Vonmonat,
  DATE_FORMAT(b.Bestellmonat, '%Y%m') AS heuteMonat,
  SUM(c.ordernum) AS Bestellungen
Von monatlichen Bestellungen ein
INNER JOIN Monatsbestellungen b
  ON DATE_ADD(a.Bestellmonat, INTERVALL 11 MONAT) = b.Bestellmonat
INNER JOIN Monatsbestellungen c
  ON c.ordermonth ZWISCHEN a.ordermonth UND b.ordermonth
GRUPPE NACH a.Bestellmonat,b.Bestellmonat;

DATE_ADD(a.Bestellmonat, INTERVALL 11 MONAT) = b.Bestellmonat

c.ordermonth ZWISCHEN a.ordermonth UND b.ordermonth

WÄHLEN
  DATE_FORMAT(a.Bestellmonat, '%Y%m') AS Vonmonat,
  DATE_FORMAT(b.Bestellmonat, '%Y%m') AS heuteMonat,
  SUM(c.ordernum) AS Bestellungen
Von monatlichen Bestellungen ein
INNER JOIN Monatsbestellungen b
  ON DATE_ADD(a.Bestellmonat, INTERVALL 2 MONAT) = b.Bestellmonat
  UND MONAT(a.Bestellmonat) % 3 = 1
INNER JOIN Monatsbestellungen c
  ON c.ordermonth ZWISCHEN a.ordermonth UND b.ordermonth
GRUPPE NACH a.Bestellmonat,b.Bestellmonat;