Tutorial 29- Aggregate Functions(Basic) Video Lecture | Postgresql: A Complete Tutorial - Database Management

otherwise welcome to another tutorial or
PostgreSQL in this tutorial we will tell
you about the aggregate functions
available in PostgreSQL so aggregate
functions are basically functions that
compute a single result from a set of
inputs so basically what our aggregate
functions is that it is used to work on
a set of rows and it returns a
particular value on working upon those
sets for example we want to count the
number of rows so it works upon the
number of rows and and gives us one
number or one particular result that is
the aggregate result of all the rules
this is what aggregate functions are all
about
so the first aggregate function that I
am going to talk about is the count star
imbued function I guess we have used
this many times in our tutorials already
so I think you should explain this
function right now so for this kritis
right select count or actually we should
just use the result first or the table
that our select star from company so you
see that I have nine records available
right now so as I told you what comes
star does is that it counts the number
of rows that means of its return be nine
if I execute the query successfully so
for that you just need to write count
and star so you see I get a count as
nine so this is useful when we have
clusters of database all we have really
big database such as a face book it has
millions of users so you cannot count
the number of rows manually so you this
is a very important function in case you
have a very big database so the next
function that we are going to talk about
is the
max function max function basically
returns the maximum from a group of data
so you could see that I want to drive
the maximum age that is available in the
company so I would see it it is 35 here
so you could see that if I do a max age
you will see that I get ready I have a
48 also available that you would see it
just check it now and yeah that is age
40 is also available that is the maximum
age so you would just use the max age
function to get the maximum age or the
maximum number that is in the set the
next operator is the min that means it
will return the minimum age that is
completely opposite to max so I don't
need to explain this so the next thing
is the average average means the mean
value of or the average value of all the
group so you could just two AVG and age
so this would return me the average age
of all the employees in the company you
can see the average age is 30 in my
company so the next thing is some some
it adds up all the rows of a particular
column like suppose I want the sum of
the age of all the employees so it could
give me the sum of all the ages of all
the employees so this was the basic of
aggregate functions in the next tutorial
I'm going to talk about some advanced
aggregate functions so thank you for
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