Item Description: Easy interface to SQL database
This review was requested by one of the module's authors, belg4mit. A
while ago, we discussed some easier ways of using DBI, and of
course his EZDBI and my DBIx::Simple were mentioned. I
will not discuss DBIx::Simple in this review. If anyone wants to review
it, please do so.
What is EZDBI?
EZDBI (Easy DBI) is a module that provides functions for database
connections, using DBI as its backend. Many people find DBI either too
hard or too much work (why fetchrow_arrayref if you can have
something shorter?), and several modules try to end that problem. EZDBI
uses no object orientation, so anyone without too much programming
experience can install and use the module immediately. I review version
Normally, modules in CPAN have some sort of hierarchy. It isn't always
consistent or well-chosen, but most modules are grouped in top-level
namespaces. DBI extensions should be in the DBIx:: namespace (that's
right, not even DBI::), but this one uses a top-level namespace of its
own. It is hard to find when searching CPAN: when using keywords like
'Easy' and 'Simple' in a module-name search, EZDBI is not one of the
results. Even when you look for modules with 'DBI' in the name, EZDBI is
unclear until you pronounce it letter by letter in English (which may
not be a natural thing to do for those who don't natively speak
English). There is a module called EasyDB, one called DBIx::Easy and one
called EZDBI. That isn't very handy.
Connecting to a database
The connecting function is simply called Connect. It's a
straightforward function call that takes either a DBI DSN or named
Of course, the most important thing you will want to do with a database
module is sending queries to the database and getting results. EZDBI
provides a function for each of the most used SQL commands:
Select, Insert, Update, Delete. If
you have a normal database select like SELECT foo FROM bar, you
would put the Select part outside of the quotes and have Select 'foo
From bar';. I changed FROM to From to match the
The Select function is rather intelligent. By default, it fetches
everything and returns it, but it can also return an object that can be
used to fetch one row at a time. Insert has a nice ??L shortcut
that is turned into (?, ?, ?, ...) with as many question marks
as the number of remaining arguments.
There is Sql for when the given functions cannot execute the
SQL you want it to. Unfortunately, this uses DBI's do, so don't
expect to be able to get information out of it (For example with mysql's
SHOW TABLES command).
Every module needs documentation. Without the documentation, I wouldn't
be able to write this review, as I didn't actually test the module
thoroughly. I did not have to, as the manual provided almost everything
I wanted to know, and the source gave me the rest of the clues. Although
the programming style itself is not the one I like, the manual is very
clear and easy to read. It is written with beginning programmers in
mind, so the EZ is worth its bits. I especially like the vivid examples.
However, I found something in the documentation that bothers me. EZDBI's
manual states that EZDBI takes care of ? placeholders, but this
module only expands its special ??L placeholder (which is in
turn only for Insert). Placeholder substitution is performed by
DBI's execute(), but up to three times, EZDBI takes credit for what DBI
This is quite a hassle with EZDBI. You can have multiple databases, but
you'll have to use Use, which can be compared to Perl's own
select that selects a filehandle. This way, copying data from one
database to another (which is not uncommon: a lot of people migrate from
MySQL to Postgres, for example) has to be done using temporary variables
and a lot of Use calls. I don't think this is EZ, object
orientation would be so much better for this.
When the Perl interpreter ends, it will destroy all variables, including
the DBI object that is stored inside of EZDBI. That way, database
connections are properly terminated. If the end of the interpreter never
happens (i.e. when using PPerl or mod_perl), you're stuck with the
database connection even after your script ends. You will have to
explicitly call Disconnect. EZDBI is not object oriented, so
there is no object to destroy automatically when it goes out of scope.
This is potentially very dangerous.
I wouldn't use EZDBI myself, but not because the module is bad. It's a very
good module, but I happen to like object orientation, and I prefer raw SQL to
semi-abstracted SQL. Maybe I'll steal the ??L idea one day, though.
If object orientation is too hard for you, or if you want to do things the
easiest way, EZDBI is perfect for you. Don't forget to Disconnect
explicitly when using EZDBI in mod_perl, because otherwise someone else might
be able to access to your database!
This is the very first module review I've ever written. Please
tell me if I did anything wrong (reply).
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