Problem writing a MySQL Function

Thanks for that, mankowitz!

I'm using cPanel and phpMyAdmin on a shared hosting environment, and I tried your command via phpMyAdmin's "SQL" menu, like this:
    GRANT EXECUTE ON PROCEDURE myaccount_mydb.Enc1 TO myaccount_user@localhost;
but got this error:
    #1370 - grant command denied to user 'myaccount'@'localhost' for routine 'myaccount_mydb.myaccount_mydb.Enc1'
So I tried this:
    GRANT EXECUTE ON PROCEDURE Enc1 TO myaccount_user@localhost;
and got this error:
    #1370 - grant command denied to user 'myaccount'@'localhost' for routine 'myaccount_mydb.Enc1'
Or should I have done:
    GRANT EXECUTE ON FUNCTION ... ?
Got the same error for that.

But after some experimentation, I found that under cPanel > Databases, if I gave the user for that database "EXECUTE" permission, then reran my SELECT command:
    SELECT Enc1(firstname) FROM person WHERE id = 1;
I then got this error:
    ERROR 1054 (42S22): Unknown column 'firstname' in 'order clause'
I don't see any order clause.  Any ideas?

Also, I'd like this command to be able to be run on any column, so how can I make it so that will work?

Thanks again.
tel2

After some experimentation, I see that this:

    CREATE DEFINER=`myaccount`@`localhost` FUNCTION `Enc1`(`IN` VARCHAR(255)) RETURNS VARBINARY(255) NOT DETERMINISTIC NO SQL SQL SECURITY DEFINER RETURN AES_ENCRYPT(firstname, 'mykey')

should have been this:

    CREATE DEFINER=`myaccount`@`localhost` FUNCTION `Enc1`(`firstname` VARCHAR(255)) RETURNS VARBINARY(255) NOT DETERMINISTIC NO SQL SQL SECURITY DEFINER RETURN AES_ENCRYPT(firstname, 'mykey')

But it could be used on any column, so I might as well write it like this:

    CREATE DEFINER=`myaccount`@`localhost` FUNCTION `Enc1`(`col` VARCHAR(255)) RETURNS VARBINARY(255) NOT DETERMINISTIC NO SQL SQL SECURITY DEFINER RETURN AES_ENCRYPT(col, 'mykey')

ok. looks good.

Thanks mankowitz.

From a quick look at the documentation, it looks as if this "DETERMINISTIC" / "NOT DETERMINISTIC" thing is just for performance.  Would this function be considered to be deterministic, given that the same parameters could produce different results depending on the value of the column passed (i.e. if firstname is always passed as the parameter, then it could give one result for one row, and another result for another row.)?

Thanks mankowitz.

When you say "changing data", do you mean:
1. For the duration of an job (e.g. a number of transactions which might run for a second or so) which uses the function, or
2. For many instances of the above
?

Thanks for that, mankowitz.  That's pretty clear.

The thing that was not clear to me before was, do those "inputs" include the data in the database.  It seems they don't.

I found this regarding SQL Server.  Might also apply to MySQL:

    "Deterministic functions always return the same result any time they are called with a specific set of input values and given the same state of the database. Nondeterministic functions may return different results each time they are called with a specific set of input values even if the database state that they access remains the same."
Source: http://technet.microsoft.com/en-us/library/ms178091.aspx

Seems to agree with what you have said.

So I guess that means my function will be not deterministic.