text stringlengths 1 81 | start float64 0 10.1k | duration float64 0 24.9 |
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but this SQLite prompt
is a very direct way | 1,302.22 | 2.22 |
of just being able to
write a query very quickly | 1,304.44 | 2.19 |
and see the results of that query. | 1,306.63 | 2.835 |
So it turns out, there are other
types of queries we can run as well. | 1,309.465 | 2.875 |
So we'll take a look at some others. | 1,312.34 | 1.5 |
We don't just need to say where
something equals something else. | 1,313.84 | 3.29 |
Other types of Boolean
expressions are allowed as well. | 1,317.13 | 2.76 |
So I could say something
like SELECT * from flights | 1,319.89 | 2.91 |
where duration is greater than 500. | 1,322.8 | 2.41 |
Where the idea here is let's
look at the duration column. | 1,325.21 | 2.81 |
It's an integer, so we can do
arithmetic expressions on these values. | 1,328.02 | 4.11 |
I can take a value and see if
it's greater than 500 or not. | 1,332.13 | 3.5 |
When I do that, what I get back
is all of the rows that have | 1,335.63 | 2.62 |
a duration that's greater than 500. | 1,338.25 | 2.34 |
I can begin to query not just
on whether one value equals | 1,340.59 | 2.97 |
another value, but also other
types of comparisons as well. | 1,343.56 | 3.96 |
Much as in Python, as when we had
Boolean expressions in Python, | 1,347.52 | 3.12 |
I could join multiple
Boolean expressions together | 1,350.64 | 2.67 |
using words like AND and OR. | 1,353.31 | 2.4 |
SQL has the same type of thing
in its own query syntax, too. | 1,355.71 | 3.6 |
I could say something like SELECT * from
flights where duration is greater than | 1,359.31 | 3.99 |
500 AND destination= "Paris." | 1,363.3 | 3.06 |
As you might logically
intuit this means, | 1,366.36 | 2.1 |
this means get me all the
flights that are going to Paris | 1,368.46 | 2.97 |
and that take longer than 500 minutes. | 1,371.43 | 2.16 |
It turns out there's only one
such row inside this table that | 1,373.59 | 3.27 |
satisfies both of those constraints. | 1,376.86 | 2.97 |
Of course, instead of
using AND I could've also | 1,379.83 | 2.13 |
used OR to get a different query where
now I'm looking for all of the flights | 1,381.96 | 6.12 |
longer than 500 minutes or
the destination is Paris. | 1,388.08 | 3.81 |
So as long as either of those conditions
are met, I'm going to get results back. | 1,391.89 | 3.93 |
So what I get back are some of the
rows where the destination is Paris, | 1,395.82 | 3.36 |
some rows where the
destination isn't Paris, | 1,399.18 | 2.01 |
but the duration is
more than 500 minutes, | 1,401.19 | 2.74 |
and of course any row that
satisfies both of these constraints. | 1,403.93 | 3.23 |
In particular, flight id number 2. | 1,407.16 | 2.7 |
That gets resulted as well when I run
this particular query on this table. | 1,409.86 | 6.028 |
There are other types of queries
I can perform in addition to that. | 1,415.888 | 2.792 |
So I can say something
like SELECT * from flights | 1,418.68 | 2.37 |
where origin is in-- and then
in parentheses-- in "New York" | 1,421.05 | 2.97 |
comma "Lima" to say, check if the origin
is in this sequence of possible values. | 1,424.02 | 4.23 |
The sequence of New York and Lima, as
long as it is one of those two, then | 1,428.25 | 4.05 |
I want for the results to come back. | 1,432.3 | 1.74 |
So then you'll get back rows that
have an origin of New York, rows | 1,434.04 | 3.36 |
that have an origin of Lima, as well. | 1,437.4 | 1.68 |
So you can begin to construct
more sophisticated queries that | 1,439.08 | 3.33 |
are able to check for whether an
origin is in a list of possible values | 1,442.41 | 3.36 |
or even if it matches
a particular pattern. | 1,445.77 | 2.97 |
That maybe you know that one of
the columns looks a certain way | 1,448.74 | 2.7 |
or is formatted according
to a particular structure, | 1,451.44 | 2.167 |
but you don't know
exactly what the value is. | 1,453.607 | 2.943 |
I could run a query like SELECT
* from flights where origin-- | 1,456.55 | 3.98 |
not equals-- but where origin is like-- | 1,460.53 | 3.36 |
and then in quotation marks, I have
a bit of a strange expression "%a%" | 1,463.89 | 5.49 |
This percent stands for a wild card. | 1,469.38 | 3.07 |
And this time the wild card is looking
at the values of a particular column. | 1,472.45 | 3.48 |
In this case, the value of the
origin column, meaning the percent | 1,475.93 | 3.2 |
stands for zero or more characters,
no matter what those characters are. | 1,479.13 | 3.81 |
We're looking for some number of
characters-- maybe zero maybe more-- | 1,482.94 | 3.09 |
followed by an A, followed by
some other number of characters-- | 1,486.03 | 3.06 |
maybe zero maybe more. | 1,489.09 | 2.17 |
And ultimately what this
query is going to do | 1,491.26 | 2.39 |
is look inside of the flights
table and get back to me | 1,493.65 | 2.97 |
all of the results where
there is an A the origin. | 1,496.62 | 3.54 |
As long as there is an
A in the origin column, | 1,500.16 | 2.13 |
doesn't matter if there are characters
before it or characters after it, | 1,502.29 | 3 |
all of the rows that come back
are going to be the rows that | 1,505.29 | 2.82 |
just so happened to have an A in it. | 1,508.11 | 2.88 |
So lots of ways we can
begin to run SELECT queries. | 1,510.99 | 2.37 |
And there are even additional functions
you can add to your select queries | 1,513.36 | 3.083 |
as well. | 1,516.443 | 0.757 |
If instead of just selecting
the values of columns, | 1,517.2 | 2.46 |
I want to compute the average duration
of a particular category of flights, | 1,519.66 | 3.828 |
or I want to count how many flights
that are coming out of New York, or I | 1,523.488 | 3.042 |
want to find the longest
flight that goes to London, | 1,526.53 | 2.19 |
or the shortest flight
that goes to London, | 1,528.72 | 1.86 |
or I want to add up all of the
durations for a whole bunch of flights. | 1,530.58 | 2.917 |
Maybe there are flights that
are connected to each other | 1,533.497 | 2.333 |
and I want to add up the total
travel time that might take. | 1,535.83 | 2.61 |
SQL has a number of
built-in functions that | 1,538.44 | 2.31 |
allow us to perform these
sorts of calculations, as well. | 1,540.75 | 3.663 |
So a couple of different SQL
commands we've now taken a look at. | 1,544.413 | 2.667 |
We've taken a look at Create Table
that allows us to create a new table. | 1,547.08 | 3.87 |
INSERT that lets us add data to a table. | 1,550.95 | 2.82 |
SELECT, which lets us take data
inside of the table and retrieve it. | 1,553.77 | 3.727 |
But, of course, often when
we're dealing with databases, | 1,557.497 | 2.333 |
the data doesn't just get added. | 1,559.83 | 1.44 |
The data changes in some way. | 1,561.27 | 1.9 |
So we also need some way of being
able to update data after it's already | 1,563.17 | 3.53 |
inside of our database. | 1,566.7 | 2.14 |
There's another query for that,
which is an Update command that we | 1,568.84 | 2.9 |
can execute on our database. | 1,571.74 | 1.92 |
And that command looks
something like this. | 1,573.66 | 1.86 |
Again displayed on multiple lines, but
you could put this entirely just on one | 1,575.52 | 3.53 |
line. | 1,579.05 | 0.5 |
SQL doesn't really care
if you add line breaks. | 1,579.55 | 2.503 |
It just knows that when it sees a
semicolon at the end of the command, | 1,582.053 | 2.917 |
that is the end of this
particular command. | 1,584.97 | 3.09 |
But here what I've said
is used the Update keyword | 1,588.06 | 2.85 |
to say I would like to update a table. | 1,590.91 | 2.243 |
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