Why '1.66' does not match 1.66 in MySQL in double-field?

I wondered, why my queries formed in Perl code using DBI did not returned correct records. I had simple queries like : ``` my $query = "SELECT id FROM table WHERE title = ? AND price = ?"; ``` I executed it like: ``` my $sth = $dbh->prepare( $query ); my ($id) = $dbh->selectcol_arrayref( $sth, undef, $title, $price ); ``` Most time everything worked fine but in some rare cases i did not get results i expected. So i tried from CLI too. Fulled query with dubious values: ``` SELECT id FROM table WHERE title = 'Some title' AND price = 1.66; ``` And got desired records back. After that i quoted price value too: ``` SELECT id FROM table WHERE title = 'Some title' AND price = '1.66'; ``` And got zero records as result. After that I tried with other quoted price values, like '1.67' and they worked fine. What is problem here? Why such simple queries fail? To reproduce behaviour i put simple schema and query up to sqlfiddle, As you may see simple query `SELECT * FROM Table1 WHERE price = '1.66' OR price = '1.67';` gives only one result. I feel, it may be related to the nature of double datatype (1.66 is represented as 1.66666666... ?), but how should i form then my queries, when i use placeholders in DBI?