As far as I know, mysql's password() function is non-reversible (but it is repeatable, of course).

reversible are: encode (by decode), des_encrypt/des_decrypt (for mysql with SSL support), aes_encrypt/aes_decrypt.

Make sure to check which mysql version you have, for these functions have changed between versions, or are only available in newer ones.

Searching with google for these words will find you many explanations.

The password hashing mechanism changed in MySQL 4.1 and upgrading could break your applications if you are not prepared. Implications of Password Hashing Changes for Application Programs.

Brief overview:
In previous versions, password() generated a 16 byte password hash. As of version 4.1.1, MySQL's password() generates a 41 byte password hash. (Don't use 4.1.0 as it's password hashing is incompatible with later releases.)

There are certain things that you can do continue using the older hashing mechanism and also to migrate to the new one. See Password Hashing in MySQL 4.1) for the specifics.

If you wants to store the passwords in a mysql database for an application, the following remark from the mysql manual is maybe relevant:

quote (13.8.2 Encryption Functions: PASSWORD(str)):

Note: The PASSWORD() function is used by the authentication system in MySQL Server, you should not use it in your own applications. For that purpose, use MD5() or SHA1() instead. Also see RFC 2195 for more information about handling passwords and authentication securely in your application.

A better practice is to calculate the SHA1 or MD5 sum of the password and store the results in your database

Both functions, MD5 and SHA1, are one way hash functions. So you can't reverse them to obtain the original 'clear' password.

To authenticate somebody, just recalculate the SHA1 or MD5 sum of the given password in your application using module "Digest::SHA1" or "Digest::MD5". Then query the databank with a simple select statement to check if the calculated MD5/SHA1 value matches the stored value MD5/SHA1 for the user in the database. In that way the password is never send in clear from your application to the database.

Don't forget that password() is a mysql function, so the following is valid usage:

my $sql = "select password('$clearpass')";
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Nothing wrong, indeed the single quotes are needed.

update: OP mentions $pass=password('$clearpass'), which might be taken out of an insert:

my $sql = "insert into tab set $pass=password('$clearpass')";
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