How to check GUID is null or empty in SQL Server Video Lecture | SQL Server Administration: Basic Tutorials - Database Management

this is part 137 of sequel server
tutorial in this video we'll discuss how
to check if a grid is null or empty
first let's discuss how to check if a
grid is now checking if a queered is
null is straightforward all we have to
do is use is null keyword let's look at
an example let's declare a variable here
let's call it my quit so this is going
to be of type unique identifier so to
check if this migrated variable is now
all we have to do is use is null
keywords like this if my grid is null
then let's simply print a message saying
grid is now if it is not known then
let's simply print grid is not now now
since we have not initialized this
variable anyway it's just declared it's
going to be now so it's going to print
this message quit is now so let's
execute this code notice we get grid is
now now let's initialize my grid with a
new grid by using new ID function since
now this variable is initialized with
another great value it's not null so
when we execute this we get great it's
not now so to check if a grid is now we
use is null keyword and here is the
example that we just looked at let's
look at another example so here is what
we want to do if a create variable is
null then we want to initialize that
good variable within you great value if
it's not now then we want to use the
existing value it has got so here we've
got a grid variable let's comment this
set statement since we are not
initializing the squid variable to
anything it's always going to be now so
it's going to come inside the safe block
and in here let's initialize that grid
variable with a new grid value and then
finally select what
we have got in that quit variable so
every time we execute this they're going
to get a different grade that's because
there's good variable is now so it's
always going to come inside the zip
block and in here we are selling that
good variable to a new good value and
that's what we are selecting on the
other hand if this grid variable has got
a value if it is not null then we always
want to use that existing value so let's
copy this grid value that we have and
set it to that so in this case it's not
null so it's never going to come inside
the safe block so every time we execute
this query we are going to get the same
grid and to achieve this look at the
amount of code we have to write you can
achieve exactly the same thing by using
ease now function the benefit of using
is not function is that the amount of
code that we have to write will be
reduced let's look at that in action now
for now let's comment this set statement
and instead of all these lines we can
simply use ease nulls function so if you
want to check if this variable is now if
it is now then we want to return a new
grid so every time we execute this we
get a different grid because this grid
variable is null so it's going to return
a new grid value on the other hand if it
is not now then this is null function is
going to return whatever value we have
in this variable so now every time we
execute this we are going to get the
same grade value and look at the amount
of code that we have to write to achieve
this here are those two examples now
let's discuss how to check if a grid is
empty before that let's understand
what's an empty grid an empty grid is
required that all zeros as you can see
here the obvious question that comes to
our mind at this point is to create an
empty grid
do we have to type all these zeros and
hyphens manually if that's the case it's
bad for two reasons as tedious and
error-prone in sequel server
you can use it query to create an empty
grid so what we can do is cast 0 as
binary and we do this we get binary data
and then we are going to use another
cast operation we are going to cast the
binary data as unique identifier so when
we do this we get an empty grid another
way is again by using the cached method
so we are going to cast 0 X 0 as unique
identifier again this is going to give
us an empty grid the benefit of using
this second select query is that we only
have one cast here here are those two
queries to create an empty gradient
sequel server to check if a great
variable has got empty grid value there
are two options one option is to compare
that grid variable with the empty grid
value let's look at this in action in
this example notice we are comparing
this grid variable with the empty grid
value since this variable is already
initialized with empty quit value this
condition will always be true so when we
execute this we get this message quit is
empty instead of comparing this variable
with the empty grid value we can also
compare it with the return value of the
cached method then we cast 0 X 0 as
unique identifier we get empty grid and
we are comparing that with the value
that we have in this variable so when we
execute this again we get the message
quit is empty if we initialize this grid
variable with a new grid so in this case
it does not have empty grid so when we
execute this notice we get the message
which is not empty so there are two
options to check if ecwid is an empty
grid one option is to compare it with
the empty grid value the other option is
to compare it with the return value of
the test method thank you for listening
and have a great day