title: MySql: convert a float to decimal produce more decimal number then the stored in back.sql file
body: <p>i want to understand this:
  i have a dump of a table (a sql script file) from a database that use float 9,2 as default type for numbers.
  In the backup file i have a value like '4172.08'.
  I restore this file in a new database and i convert the float to decimal 20,5.
  Now the value in the field is 4172.08008
  ...where come from the 008??
  tnx at all</p>