SQL Tutorial - 19: The WHERE Clause Video Lecture | Microsoft SQL for Beginners - Database Management

hello guys welcome to my channel this is
the 19th tutorial in this course and in
this tutorial we are going to talk about
the where clause and we've seen the
where clause in action quite a lot you
know now that we've you know discussed
the comparison operators and the you
know logical operators and we know what
the purpose of where clause in you know
our queries is but you know I just
thought that since it's such an
important Clause I should have a
separate tutorial on it right so the
where clause is you can see it is used
you know when you have to specify a
condition that has to be obeyed while
you know data is being pulled from your
tables so you know we've seen you know
how the where Clause works and you have
to use it with the Select query and you
know another application of where clause
is that you know it's also used to you
know perform joint operations and we're
going to talk about joins later on and
you know the kinds of joints and how
where Clause allows us to join tables
but you know it is used for that too and
it's it's also used with the update and
delete ways so it's not just used with
the Select statement it's also used with
the update and delete statements and
we're going to see how it functions
there when we discuss the updating
delete queries and the syntax of the
where Clause is pretty simple and the
reason why I've placed within square
brackets is because it's optional you
know it's not necessary for you to have
a where clause in your you know query if
you're pulling out all data and if you
just want to see data as it is in the
table then you do not have to use the
word laws only if you want to reduce the
result set to you know a reduced value
by imposing some you know restrictions
or you know by placing some conditions
then you have to use the word laws and
I'm just going to show a couple of
examples you guys of the where clause in
the mindscape environment you know just
to sort of reiterate or you know
emphasize further on the points that
i've already made this presentation and
in the last few tutorials so I've got my
MySQL workbench share and in the test
database I have the employee table and
you guys are familiar with the data
that's there in the employee table and
the structure of the employer tables I'm
not going to waste any time you know
showing the structure to you guys again
and I am sure
you guys are all so bored you described
in the Select star statements by now so
let's just jump right into an
application of the word flow so I'm
going to type in the asterisk symbol
here because I want to see all data from
all fields I mean not all data but you
know data from all fields and then I'll
type in the from keyword and specify the
name of the table which is employee and
on the next line I'll type in the where
clause and I'm going to find out you
know details of all employees who have
age greater than 25 right and I put in a
semicolon to terminate the statement
when I press the ctrl enter key
combination I see you know Howard has
aged 29 stan is age 26 and roger has age
32 so we get only those values that
satisfy this condition and this is one
condition and you can have as many as
you want you can join conditions using
the logical operators that we discussed
in the last tutorial and there are lots
of other fancy things that you can do
you know by now I'm sure you've already
started experimenting with the logical
operators and the comparison operators
if you've started combining them
together to create complicated
conditions so you know you have you can
do all of that but to sort of implement
those conditions in your queries you
need the where clause right so that's
what the where keyword does in SQL and
it's really important and I just
demonstrate another way to you this time
I'll use the name field and I'll use the
equal to symbol and since name is a
character field I have to you know type
in my value within single quotes and
I'll check out data for Curt right press
control enter and there you go you know
the condition is obeyed by just one row
so you know the employees name is
obviously good and the ID is 19:15 and
the age is 34 in the email addresses
there and Curt well there is no data
available for the salary field for Curt
right so that's it about where clause I
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