Using a Float Column in a Where Clause
I spent about 12 hours today trying to figure out why one of my validates_uniqueness_of constraints was not working. Here's why:
mysql> create table some_table (some_float_column float);
Query OK, 0 rows affected (0.01 sec)
mysql> insert into some_table (some_float_column) values (8.4537);
Query OK, 1 row affected (0.00 sec)
mysql> select * from some_table where some_float_column = 8.4537;
Empty set (0.01 sec)Notice how I'd just inserted a row with that value yet the row was not returned. All I had to do was change the float column to a decimal column.