Beginner PHP Tutorial - 199 - Connecting to a Database the OOP Way Video Lecture | PHP for Absolute Beginners: From Novice to PHP Master - Web Development

hi this is Alex from PHP academy' de org
and this is a PHP video tutorial for the
new Boston now in this tutorial we're
going to be connecting to our database
but we're going to be using a class to
do this and we're also going to be using
a constructor to initiate some variables
first of all when we initiate this class
when we create a new instance of this
class so what we're doing is we're
taking a few things that we've learnt
already and we're applying them into a
real-life situation or real-life
application rather so the first thing I
want to do is obvious I'm going to
create a new class so this class is
going to be called database connect so
let's open that up into our block so we
can start writing what we need inside of
it
now the first thing we need is a
constructor and what this is going to do
is it's going to take the host name the
username and the password
and it's going to apply this to a method
inside of our class so we're only
working with one class here but we're
using a constructor first of all to take
in some variables and then what we're
doing is we're using a method inside of
our class to actually connect to the
database now if the database connect
successfully we're going to return true
and then in the constructor we're going
to rotate this value we're going to
return either true or false from the
method and in the constructor we're
going to pick up on either this true or
false value and then echo if we've
successfully connected or if we have
them so it's a bit of a long way round
of things however what we're actually
doing is practicing that's the main
thing we're practicing okay so the first
thing we need to do is create our
constructor so I've got here I'm going
to say public function two underscores
and Constructicons
strucked okay so remember the
parentheses at the end we're going to
put our arguments in there in a moment
and then our block here remember that as
well so if you don't remember what a
construct does let me just demonstrate
let's just echo out hello now let's come
down here and create a new instance of
our class by saying connection equals
new database connect now what this does
is is as soon as we initiate this class
as soon as we create a new instance of
it this code inside this block will be
run that's basically what we're looking
at when we see this constructor here so
you can see that we've run the text
hello however if this was to be a normal
function or normal method we wouldn't
automatically echo anything out so let's
get rid of that and let's get rid of
that then we need to think about what
parameters we need to pass through into
our into our class as it's created so we
need the DB host which is the database
host and you can name these anything I'm
just calling them disks up this is what
I'm used to DB username and DB password
okay
so let's give this a test so let's echo
out the DB user the DB host sorry and
append a break onto that and the DB
username append another break onto that
and the DB password so we're basically
now testing when we create the new
instance of our class our database
connects class we're testing that the
parameters are being sent through
correctly so let's say connection equals
new database Connect now in here we need
to submit a supply some parameters if we
don't you'll see that we'll get an error
says here blah blah blah missing
argument one two and three and then
we've got an undefined variable in here
as well because we haven't supplied the
arguments these are all undefined
variables and the argument error came
from here which you could see missing
argument
so let's supply it with the arguments
that requires we've got one two and
three the first one I'm just going to
say localhost I'm going to say rue and
I'm going to say password
so let's go and refresh and you can see
that that's simply taken the constructor
and it's echoed out the arguments that
we've passed into it so we know that
that works now get rid of this now what
we're essentially going to be doing here
is performing a check to see if another
method returns a true or false value
let's go ahead and create that method
now so we know exactly what we're doing
now the method is going to be called
connect and inside this method we're
going to be making use of the MySQL
connect function so what we're
essentially doing is we're saying if and
we're saying MySQL connect
and then we're supplying it with a few
arguments in here which are going to be
gained from inside here so it's getting
quite complicated and multi-level now
but hopefully by the end of this you'll
understand what's going on if this MySQL
Connect is true then we're going to
return the true value which is going to
be picked up by our constructor so we've
created the skeleton outline for our
connect method now let's go let's apply
these parameters so it's DB host DB
username and DB password so what this
will do is this will allow us to feed in
some parameters or arguments into this
connect method and we're going to do
that inside our block code here so what
we're going to do is we're going to say
if this and inside this connect then we
sang DB host DB username DB password
if this is true do something otherwise
do something else so in here I'm going
to say if not if this doesn't return a
true value so if the Kinect doesn't
return a true value it's safe to say
that the connection has failed so we're
going to put connection failed otherwise
they're going to echo connected to and
then we're just going to display the
data base house that were connected to