Tutorial 31 - LIKE in PostgreSQL Video Lecture | Postgresql: A Complete Tutorial - Database Management

hello guys welcome to another tutorial
PostgreSQL in this tutorial i'm going to
talk about like operator like operator
is a very useful operator in any form of
sequel so I have decided to make a
separate tutorial on this operator so
like operator is basically used for
batch of pattern matching and it is used
to match text against a pattern using
wildcards by wildcards I mean we have
two basic wildcards in any form of
sequel that is the percentage sign and
underscore symbol so we're going to talk
about that later
so like operator can return two values
that is a true value or false value so
for example if a pattern is matched and
we get back the result so the like
operator it returns a true value and if
we do not get the pattern or the pattern
did not match then we get a false value
for that so as I told you about the wild
cards that are the percentage symbol and
the underscore symbol so the percentage
symbol basically represents any amount
of numbers or characters for example
percentage symbol it can consist of a
single character or two characters or
three characters or for any amount of
infinite character while and underscore
symbol it is a representation of a
single character only like if I want to
extract a single character I can you
know I can just place one underscore and
if I want to get it to stimulate see I
have to place two or three underscores
in that way
while in percentile like suppose I have
a name that has five letters and I want
to extract the whole name if I put if I
put if I put a percentage there it would
extract all the file name all the five
letters of the name so next we're going
to talk about some examples so first of
all I have just selected the database
you can see that select star from
company so I will show you the like
operator on names so for example
I want to select all names that begin
with P there you could just write the
query that is select star from company
where name like P percentile so as I
told you percentile means it could take
up any number of characters after P so
you would see it now and I execute you
see I get to a name that is Priya and
pray arc and you see here after P I have
any amount anything anything after P it
accepts so this is the use of the
percentile character and one thing you
have to always remember is that the like
keyboard is case sensitive for example
if I replace the P here with the small
case P you will see I get no results now
so you have to take care of this always
that this is case sensitive so as I told
you about the percentile symbol so it
considers anything after be any number
of characters after P so this is the use
of the percentage symbol next example I
will show you like I want a in the or I
want are in the second position and then
I want a in the third position so how
will I do that now suppose I told you
about the underscore character that
means I want a in the second place and I
want sorry I want R or the second place
and I want K as a third one and rest
anything it can be anything
so here underscore means that one place
has been already occupied this means one
character it could be anything
second character should be a R and the
third character should be a and rest
anything so I am expecting a name prior
here
you could just click on execute MC I get
the name okay so the next thing that we
want is that I want an a anywhere in the
name that is it can be the first
position it could be anywhere in the
middle or it could be the last position
so for that what I need to do is put a
percentile in the beginning put in that
way means kid it could be any position
like anything could occur before a and
this means anything can occur after a so
if I click on run you would see that I
have names that contain at least one a
in them so the next is like I want a
name that is starting from P and I
wanted to be at least five characters
long so you see this so you can see this
it is at least five characters now
starts from P has to be one two three
four and five characters long so now
supposedly if I wanted it should be at
least seven care to know but just two
two more see oops I missed something
yeah this is six not seven so yeah this
is how you mention at least how many
characters long it should be next one is
I want a name that ends with a so
awesome title a just the opposite of the
first letter P you could see I get two
results now so the next thing I'll do is
I want an A at the second position but I
want it to end with G so I have no
result such as you will see I get one
result now at the second position I
should have an e and it should end with
a and the last thing that we're going to
do is I want a name that should be five
characters long first one should be H
and two three four and the fifth one
should be K so see I get the same result
again this is five characters now see
the dashes
so this is how you mentioned a fivehead
long name and it starts with H and ends
with a so I thank you for watching this
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