Tutorial 33 - Inner Join Video Lecture | Postgresql: A Complete Tutorial - Database Management

elevate welcome to our tour PostgreSQL
in these two days I am going to tell you
about inner joins so inner joins is
basically a join that is made on two
different tables in any SQL so what it
does it basically creates a new list of
table by a common field that we have in
both the tables so let me give you an
example so you would be wondering that
when we make two columns when we make
two tables why do we make a column that
has similar values to each other for
example suppose we made this company
table and we see that we have an ID so
why do we need an ID here and secondly
if you see the department table you see
we have another ID so these two values
are same or these two have the same
column so that we could create a join on
this so now I hope you would basically
understand the basic concept of why do
we need the same columns in two
different tables so these are used to
join them and this procedure is known as
the inner join so two two tables can be
joined together with a similar column
between them and that is known as the
inner join so as you can see here that I
have a value that has ID number two here
in the company table and now I have an
ID number two here in the department
table too
so you just see now that we will create
a join on these two tables so I'll just
open the text editor now
so the way to create a join is the first
method I will show you a very basic one
that is the select name age address and
department from company and we make an
inner join on Department on the ID that
is we have the similar ID so her company
is the table name company that ID means
the ID of the company table and
department of IIT means ID of the
department table if you don't give
company and department it will create an
alias and hence the SQL would get
confused about which idea are you
talking about so we need to mention that
it is the company not idea that we are
talking about and the department or ID
that we talking about so here we create
an inner join on company table and
department table on this column that is
the similar column so you could just run
this and see that I get a similar value
so you can see that these three values
were in the company table that is the
name age and address and the department
value was in the department table and
you can see engineering for two and you
see that this has been joined now so
this was the first method you could
create an inner join the next method is
you could just write the same thing and
you could just create an alias so what I
mean by alias is like you write from
company C means you could access company
now by the name C or C is an alias for
company and Department B where C dot ID
is equal to D dot
so here as I said that you could access
company now with the name C and the
department with the name D and similarly
we created and join on the ID that is C
dot ID and dealer ID so you could run
you see that we get a similar result so
thank you for unit rolls of riflemen and
stay tuned