[Please copy the mailing list on replies.] On Thu, Dec 15, 2005 at 07:32:54PM +0100, Adam Kolany wrote: > Michael Fuhr napisa?(a): > >On Thu, Dec 15, 2005 at 11:03:55AM +0000, Adam Kolany wrote: > >>stoff=> select sum(wplyw),sum(wydatek), sum(wplyw)-sum(wydatek) from > >>rachunki where okres<6; > >> sum | sum | ?column? > >>-------+---------+---------- > >>73745 | 6712.55 | 67032.5 > >>(1 row) > > > >What data types are wplyw and wydatek? > > > they were float(2) > > casting them into numeric helped, so I have changed the types of the to > numeric, instead of float(2) > > this is however a bug, I think.
float(2) gives you a real, aka float4 (32-bit floating point). As the documentation points out, that type has a precision of 6 decimal digits; you seem to object to the rounding: test=> SELECT 73745::float8 - 6712.55::float8; ?column? ---------- 67032.45 (1 row) test=> SELECT 67032.45::float4; float4 --------- 67032.5 (1 row) test=> SELECT 73745::float4 - 6712.55::float4; ?column? ---------- 67032.5 (1 row) That's arguably not a bug: you've requested a low-precision data type so you have to expect discrepancies around that 6th digit of precision. If you need greater precision then use a double precision (float8) type, or if you need exact precision (e.g., for handling money) then use numeric. -- Michael Fuhr ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
