MySQL Database Tutorial - 31 - ALTER / DROP / RENAME TABLE Video Lecture | MySQL (Sequential Query Language) Database Tutorial - Software Development

what is going on guys welcome to your
31st my SQL lesson and in this tutorial
I want to finish up kind of talking
about messing with tables the last main
things that we need to talk about the
first thing is I already showed you guys
how to create a table and how to make
like all the datatypes and columns and
stuff but what if you want to maybe add
an additional column maybe you make your
table and say okay this is good but you
have your website up and running and
about a month later you're like dang I
really need an extra piece of
information when people sign up so let's
go ahead and learn how to do that
anytime you already have an existing
table and you want to add a column you
can do it in one of two ways I'll show
you guys the first way alter table and
we'll just go ahead and alter this bacon
table right here so go ahead and write
the name of your table after which is
bacon and if you want to add a column
just go ahead and hit add and then write
the name of your column the new one
which is sample column or whatever and
then of course just like whenever you're
creating a column for the first time you
need a data type which can be well it
doesn't really matter for this example
I'm just going to make a bar chart with
ten so now what this does whenever you
run this query it's going to add a new
column to this bacon table which is
called sample column which has the data
type of varchar' ten simple enough now
in order to drop a column or in other
words delete a column from this table
let's go ahead and run another query
it's basically the same thing but
instead of add you hit drop column in
I'll discuss the differences later on so
alter table basically means change the
table bacon and drop column now what
column do we want to drop well it turns
out that we didn't need that sample
column after all now the other thing
that's different aside from add turns
into drop column you know how when we
added a column we needed to specify the
data type well whenever we're dropping a
column MySQL it doesn't really matter
what that data type is it just cares
about the column name so if we go ahead
and run this right here it's going to
say it's going to give us you know other
confirmation do you really want to
that column yes we do go ahead and hit
okay and now our column is dropped so
that is one way that we could add
columns in drop columns another way is
and sometimes you may want to do this
whenever you want to kind of preserve
the data and just make a new table you
can just go ahead and make an entirely
new table so say we had this bacon table
right here bacon has ID username and
password now if I wanted to make a new
table with an additional column but I
didn't wanna you know maybe mess up this
table or I was afraid of editing it what
I would do was I would create an
entirely different table maybe name it
bacon - or something like that and I
would take all of this data and import
it into bacon - and that way if I messed
up anything I still had just this
original table so that is another
variation that you can do that so say
that you did that and now all of your
data is successfully transferred into a
new table called bacon - well now we
want to get rid of this bacon table
because hey it's just taking up space on
our database so in order to delete an
entire table here's how you do that drop
table bacon now whenever you do this be
absolutely sure that you never want to
use the table again so I'm going to go
ahead and delete this and it's going to
give us our confirmation and not only
does it delete the table but all of the
information so again make sure that you
definitely are very careful with this
command so a drop table okay the bacon
table is dropped so now actually now
that I think about it I probably should
have done these last two little lessons
in reverse order I'm going to show you
guys how to rename a table so now that
we don't have bacon to work with anymore
I guess I can't rename it to anything
like sausage or anything but check this
out you know how we have this customers
table and it kind of has all the users
information well I've been doing these
tutorials and I was kind of thinking you
know what would it be handy if this
customers table was actually named users
instead huh that would be maybe make
things a lot more clear so what if I
could rename this table customers too
users wouldn't that be nice yes it would
so let's go ahead and learn how to
rename a table anytime you want to not
you know import data don't mess with the
data at all just change the title of the
table go ahead and hit rename table
and then give it the name of your
original table which is customers and
now go ahead and write two and then give
it a new name so I want to rename the
customers table to users so I'm going to
go ahead and run this and it's going to
say okay your query has been
successfully executed
now it doesn't update here but if you go
ahead and look on your database you can
see that it does indeed update so I just
want to mention that not only with you
know whenever you're renaming stuff but
sometimes whenever you're deleting
things in PHP myadmin it takes a little
bit to update on the left hand side but
if you go ahead and I you know exit out
then look back in it should be updated
so anyways that is how you change um
columns add columns drop columns delete
tables rename tables so now that's
basically all there is for table wise
how to create tables and mess with
tables so in upcoming tutorials we're
going to be learning about some advanced
techniques that go beyond the basics and
for right now how can I say this you are
an intermediate MySQL user but the next
10 tutorials are going to take you to
the next level they're going to be
awesome and amazing so thank you guys
for watching don't forget to subscribe
and I will see you guys then