How to join
4 Tables In Mysql
MySQL tutorial 16 - joining many tables
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hey YouTube how's it goin it's Quinton
here and welcome to this tutorial on
joining tables and yeah in the previous
tutorial we take took a look at joining
two different tables but I just wanted
to take a little bit more of an in-depth
look at this because in that tutorial we
only join two tables and yeah you can
actually join more than two tables so I
just wanted to give you guys an example
of how that works but before I start off
this tutorial I do want to send a huge
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with the tutorial so go over to the
learning over here database that we
imported in the first tutorial and
there's actually a very very specific
table that I created exactly for this
tutorial which is the orders table so
click on that and if you inspect this
orders table you'll see that there is an
order ID a product ID a user ID and an
address ID so basically this table has
just full of IDs there's no actual
information in here and if we browse
this you can see that yeah it's
basically just the table with a bunch of
numbers in it so there's not really much
information that can be sourced out of
this table
so this is where joins perform their
best and yeah it basically means that
all of the information that's in the
other tables I did not have to repeat
when I put when I created this table
basically I just grab the IDS of the
other tables and I put them into this
table and now I can gather any
information I'd like from those tables
whenever a viewing in order so basically
I can see that I have an order over here
and this is order with an ID of 1 and if
I wanted to see what product they
ordered I could link to the product
table and get any information about that
product just using that product ID I can
also link to the users table and get any
info
nation about that user using the user ID
and of course I can grab the address
that that user asked the product to be
delivered to by checking out what's in
the addresses table and using the
address ID so now let's take a look at
where this would be useful and I'm going
to write a query over here so go ahead
and just remove everything that's in
here at the moment and let's type select
and I think let's start off by just
selecting from two tables because that's
how I like to build my queries is just
like try keep them simple and then add
more and more stuff on as it gets
complicated although this is going to be
a very easy tutorial so don't be dumb be
scared but yeah let's say select and
we'll select the orders dot order ID so
now we're selecting something from our
orders table and I think the next thing
we should select from is going to be
from the products table so let's select
the product name so you can see what the
what what order was placed and what
product they ordered so let's select
products dot product name so now we've
got our two fields we can type in the
from keyword and then I can select the
first table which is going to be orders
and then join on my second table which
is going to be addresses and I want to
join these where the whoops I'm going to
be addresses it's going to be products I
totally spaced out there for a second
but yeah it's going to be products and I
want to join these tables where the
orders dot product ID is equal to the
products dot product ID so let's go on
orders dot product ID is equal to
product dot product ID because those are
the two fields that are in both of these
tables and now let's copy this and hit
go and now you can see that we have an
order ID with an order of one so our
first order went to or was for a blue
lightsaber and now I think it'd be kind
of interesting
to see who this order went to so I'd
like to add on information from the
users table because we know that the
information about who this would be
going to is going to be in the users
table so let's go over to the SQL tab
here and let's copy my query back in
here and to add on another table is
super super simple all I do is I add in
a comma over here and I select the next
field that I want to select so in this
case I want to select something from the
users table and I think we can select
the users first name so go ahead and
select something from the users table in
this case I want to use the first name
and then just add in another join at the
end of your query so basically we've got
this first join here which joins the
products products table and now we'll
have a second join that's going to join
the users table and that's going to join
it on where orders dot user ID is equal
to users dot ID right and again the
reason why I'm using that field is
because our orders table has a user ID
and our users table also has a user's ID
so it's the field that links both of
those tables and let's hit go so let's
just ignore that text and move on and
we've already selected from three
different tables so order I orders ID
from the orders table product name from
the products table first name from the
users table and the last table that we
have yet to select something from is the
addresses table so let's go back here
and add in something from the addresses
table so I'm going to add in a comma and
let's select the addresses city and
we'll simply join that where the address
well where the orders dot address ID is
equal to addresses dot address ID and
now let's copy this
and hopefully I don't have any errors so
let's hit go and I okay yeah I have made
a really stupid mistake yet join we want
to join addresses on orders dot address
ID yeah okay make sure that you follow
that exact same syntax and now let me go
ahead and copy this just in case I want
to write this query again and hit go and
it looks like I don't have any errors
this time so and now I can see that our
first order was a blue line saver that
went to Luke and it's going to Naboo and
the same thing with our second order
that's a stormtrooper uniform that's
also going to Luke and it's also going
to Naboo what's he up to I wonder and
yeah that is how to join four different
tables together using my SQL and
hopefully you find this tutorial helpful
and I hope that you'll go around using
the information that you learned in this
tutorial to join as many different
tables as you can but before I end off
this video I just want to send a huge
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guys in the next one
![how to join Multiple table in mysql [ Inner Join , Left Join, Right Join ]](https://img.youtube.com/vi/lKPQ94VjySI/mqdefault.jpg)
