Mysql update field, presission on floating numeric field problemsl

Question

I have 2 tables, both having a field of type float(12,4).

lets say table1.field1 float(12,4) and table2.field1 float(12,4)

as you see the fields are declared the same

the issue is when updating these fields. if I update these fields with the same value, they will store different values.

insert into table1 (field1) value (101.4904); update table2 set field1=field1 + 101.4904

after these sql statements the fields will have a difference of 0.0018

this is tested on my local computer so there is no other updates made to the database.

any clue what is causing this difference?

http://stackoverflow.com/questions/5150274/difference-between-float-and-decimal-data-type?s=1|1.3169 — Hanky Panky, Nov 04 '14 at 10:12
http://stackoverflow.com/questions/13030368/best-data-type-to-store-money-values-in-mysql/13030389#13030389 — Hanky Panky, Nov 04 '14 at 10:13

score 1 · Answer 1 · answered Nov 04 '14 at 10:05

1

float is a inaccurate data type by definition. If you need exact precision then use decimal(15,6) for instance

answered Nov 04 '14 at 10:05

juergen d

1 Answers1