Retrieving float value from table

Question

I have a field in a table "url_key_weight" with float data type. In one record i have value 2.95 in the float field. When I retrieve and print it from PHP code, it prints 2.9500000476837. But when I run the following querys from PHP

"SELECT * FROM url_key_weight WHERE bid = 2.95"

OR

"SELECT * FROM url_key_weight WHERE bid = 2.9500000476837"

I get nothing.

@fancyPants url_key_weight is table name and bid is column name. and yes bid is float — G. M. Nazmul Hossain, Jul 08 '13 at 08:13
Try enclosing the numbers in quotes vis '2.95' and see what happens. Is your field type defined as float? Would varchar perhaps be a better way to do it? — Robert Seddon-Smith, Jul 08 '13 at 08:13
http://stackoverflow.com/questions/2567434/mysql-floating-point-comparison-issues — golimar, Jul 08 '13 at 08:21
Why are you using FLOAT at all? DECIMAL would seem more appropriate. — Strawberry, Jul 08 '13 at 09:13

score 1 · Accepted Answer · answered Jul 08 '13 at 08:38

1

To have a direct compare you'd have to round

SELECT * FROM url_key_weight WHERE ROUND(bid, 2) = 2.95

Read more about it here.

answered Jul 08 '13 at 08:38

fancyPants

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So? Do you want to get that row, too? Or is it returning this row although you don't want to? – fancyPants Jul 08 '13 at 11:39
Also, if you care so much about having correct values, then you should use the decimal datatype instead of float. – fancyPants Jul 08 '13 at 11:41

score 0 · Answer 2 · answered Jul 08 '13 at 08:18

0

it is not generally a good idea to compare floating point numbers with = equals operator.

try out this

"SELECT * FROM url_key_weight WHERE bid >= 2.95"

answered Jul 08 '13 at 08:18

Vijay

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But I have another value 2.96 in bid – G. M. Nazmul Hossain Jul 08 '13 at 08:19

Retrieving float value from table

2 Answers2