GROUP BY Stock.Date;If a date appears more than one time then it must appear more than one time.
INSERT INTO stock VALUES ({^2012-07-01},0,0,0,0,0,0,15,30) INSERT INTO stock VALUES ({^2012-09-09},0,0,10,0,0,0,0,0) INSERT INTO stock VALUES ({^2012-09-09},0,0,15,0,0,0,0,0) INSERT INTO stock VALUES ({^2012-09-10},0,0,10,0,0,0,0,0) INSERT INTO stock VALUES ({^2012-09-11},0,0,0,15,0,0,0,0) INSERT INTO stock VALUES ({^2012-09-21},0,0,0,0,30,60,0,0)Date ({^2012-09-09} is more than one time. So it must appear as it.