Question

I have an application that works with database (PHP + MySQL).

One of the columns in the database table is of type ENUM('VALUE1','VALUE2').

Is that possible to add safely VALUE3 to the ENUM without damaging the data in the table ?

Answer 1

if you add to the end is seem safe , see the manual

For some operations, a “fast” ALTER
TABLE is possible that does not
require a temporary table:
….
Changing the definition of an ENUM or SET column by adding new
enumeration or set members to the end
of the list of valid member values.
(Adding members in the middle of the
list causes renumbering of existing
members, which requires a table copy.)

read in :

http://dev.mysql.com/doc/refman/5.1/en/alter-table.html

also good point look in the article:

http://www.brandonsavage.net/why-you-should-replace-enum-with-something-else/