SQL Tutorial - 21: The UPDATE Query Video Lecture | Microsoft SQL for Beginners - Database Management

hello guys welcome to my channel this is
the 21st you Doyle in this course and in
this tutorial we'll be checking out the
update query in SQL so what is the
update query useful as a name suggests
the update statement is used to update
or change values or records or rows in
your table right and you generally use
the update query with the where clause
and there'll be very few cases when you
wouldn't be putting the work laws in
your update query and those will be the
cases when you want changes to happen
across the table that is across all rows
in the table right so if you want you
know a particular field to be affected
for all rows in the table then you use
the update query without the where
clause in all other cases you would be
putting in your where clause in your
update queries right and we're going to
check out an example of the update
statement in the Meister environment but
before that let's have a look at the
syntax of the update statement so the
syntax is pretty simple you have the
update keyword and then you put in the
name of your table on the next line you
put in the set keyword right that's SAT
and then after that you put in the names
of the columns that you want to you know
sort of update and you know with the
corresponding values right and on line
number three you put in the where
conditional since it's optional I have
you know mentioned all of that within
square brackets so let's have a look at
an example of the update statement in
the MySQL environment now so I've got my
MySQL workbench and you know just as we
have in the previous tutorials we're
going to work with the employee table in
this tutorial too and it's in the test
database I'm not going to show you guys
the structure of the table because I'm
sure you guys are familiar with it
already but we're going to look at the
values that we have in the table at the
moment right and since I want to see all
records in all fields I'm going to use
the asterisk symbol to pull out the data
and you know I put in the prom keyword
and the name of the table on line number
two and when I press control enter I see
that I get all the rows and there are
quite a lot of records in the table and
the fields we already know what the
fields are now let's say I want to
change the age of John from 22 to 26
I'll have to use the update query
you know to do this and there are other
ways of doing this by you know simply
using the GUI interface and I'm going to
talk about that in a bit part you know
let's see how we achieve this using the
update way so I'm going to close this
result set and on a fresh line I'll type
in the keyword update and then the name
of the table which is employee right on
line number two I'll type in the keyword
set then the column that I want to
change or update right and in this case
that is age and then I'll put in the
assignment operator or the equal to
symbol and the value that I want this
column to have so I want to change the
age to 26 so I will be typing 26 and
since age is a numeric field I don't
have to put 26 within single quotes if I
was updating the name then I would have
put the new value within single quotes
right and then on the next line since I
don't want all the records you know to
be affected I want just John's age to be
changed I'm going to put in the where
clause here and I will put in a
condition right so what is that one
condition that uniquely identifies the
record for John right there could be
multiple entries in the table that have
the value John in the name field right
so you just want to change the value for
John that has the ID 1900 right so you
have to look for the primary key here
and since in our table the primary key
is the ID field I'll be using the ID
field in the word condition and you know
the value for the ID field for John is
1900 right so I'll put in that and a
comma so SMI semicolon at the end of the
statement and when I press control enter
I see that I get a message in the output
section that the update statement has
been executed successfully and now when
I execute the select star from employee
query I see that the updated value of
John is displayed right so John's age
now is 26 so this is about the update
query in case I would have not put this
where clause in the update statement and
what would have happened is that you
know the age values for all the
employees would have been
2:26 right so Peters age would have been
changed from 24 to 26 Howard's a it
would also have been changed from 29 to
26 so all rows would have been affected
but you know since I have included this
it restricts the scope of the update
update statement to just the record you
know where the value of the ID field is
1,900 and that is a record for John
right and another way in which you can
change values in your tables and you
know this is something that you can do
in MySQL and you know only through the
workbench obviously not through the
command-line interface and this is not a
part of SQL but I'm just telling you
guys in case you want to know how to do
this
you know you select a field right and
then you change its value right so if
suppose I want to change Peters age to
30 I put in 30 here and then I close the
results in before I close it you know
MySQL workbench you know it brings in a
dialog and it asked me whether I want to
apply some changes that I made to some
values in the result set if I click on
apply you know then you know it tells me
that this is the query that I would have
to execute so it is going to execute the
update statement but you wouldn't have
to type it right so when I click on
apply you know it finishes it and now
when I execute the Select star query I
see that the updated value of 8 shows up
so in a sense you are executing the
update query but you're not executing it
yourself you know you sort of you know
assigning the task of doing of executing
the update statement to MySQL but I
would recommend you guys to practice the
update for yourself so that you get
familiar with it and you feel
comfortable using it and anyway thanks
for watching this tutorial and please
subscribe to my channel in case you
haven't already I'm going to see you in
the next one in which we'll discuss
something interesting and important for
sure and take care to learn