MySQL Database Tutorial - 5 - Basic Rules for SQL Statements Video Lecture | MySQL (Sequential Query Language) Database Tutorial - Software Development

on the subject of queries I guess I
might as well teach you guys well I
guess I might as well go over a few
things before I continue with these
tutorials first of all whenever you make
a query or command in your results are
not in the same order as mine don't
worry it doesn't mean it's broken or it
doesn't mean you know yours is messing
up or mine is messing up these aren't
sorted or they aren't filtered or
anything I'm going to be teaching you
guys about filtering and sorting your
results later on but for now just make
sure that as long as you get the results
of cities from the right table then
everything is good to go
another thing is whenever you run your
queries you can run multiple queries or
commands at a time for example you can
select City from customers and you can
also run another command at the same
time for example arm select ID from
customers ID now take note that whenever
you run multiple queries at the same
time then they must have a semicolon at
the end whenever you just run one the
semicolon is optional but whenever you
run multiple queries like this then as
you can see it must have a semicolon at
the end of each one so I just want to
point that out and also whenever you're
working in the command line then you
don't have that option of with one query
in phpMyAdmin the semicolon is optional
but if you're um watching these
tutorials for school and you're running
these in the command line then please
make sure that you have the semicolon
because the command line is very picky
and needs that semicolon at the end
another thing is that and I probably
shouldn't even tell you this to be
honest but I'm gonna because I just want
to teach you guys everything you know
how I said that by standard SQL is
capitalized and everything else is lower
cased well that's the standard but it
isn't 100% necessary s qo is not
case-sensitive you can run something
like this select City from customers and
you can go ahead and run this
query and it's going to run just fine
however it's not standard it's really
hard to read when you do that and if you
do this for a company you will literally
get fired if you do this that's how much
people hate it so please even though you
can do it please I'm begging you don't
like I said I probably shouldn't have
even told you guys about that now the
last little rule I want to talk about is
this whitespace and multiple lines are
ignores for example whenever I run a
query like select city from from
customers wow really messed that up
customer okay
take a deep breath customers like that
I'm just go ahead and copy this real
quick I can run it and it's going to run
just fine however I can also run it with
a bunch of white space in between and
white space are just characters pretty
much spaces that don't do anything I can
go ahead and run this and it's going to
run just fine and last but not least I
can go ahead and even put a bunch of
lines in between here go ahead and run
it and it will run just fine so the
reason that they made it set up they set
up the language to do this was for
readability purposes say you wanted to
only write one MySQL keyword per line
well you can go ahead and write it like
that and it's fine it doesn't affect the
results at all it's just for your
purposes whatever you think is the best
basically whenever you're working for a
company whatever your boss says that's
what you got to go ahead and do but if
you're working on the website your own
just whatever you think is the easiest
to read then do it so white spaces and
line breaks are totally ignored they
don't have any effect on the results so
that is all you get for this tutorial I
know a lot of information but in the
next story what we have to do is we need
to learn about more commands other than
show and select so um thank you guys for
watching don't forget subscribe and I'll
see you guys in the next video