text stringlengths 1 81 | start float64 0 10.1k | duration float64 0 24.9 |
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So I could say something like
select * from flights where id= "3." | 997.31 | 4.31 |
Again, this reads as very English like. | 1,001.62 | 2.29 |
I'm saying select all of the
columns from the flights table, | 1,003.91 | 3.78 |
but not all of the rows. | 1,007.69 | 1.32 |
I only want to select the rows where-- | 1,009.01 | 2.76 |
this is a SQL keyword-- | 1,011.77 | 1.38 |
where id= "3." | 1,013.15 | 1.8 |
ID is the name of a
column, 3 is the value, | 1,014.95 | 2.67 |
and it's going to look through this
table, only find me the flights | 1,017.62 | 2.85 |
where the id is equal to 3, and I'll
just get back that one row as a result. | 1,020.47 | 4.77 |
It finds the row with an ID of
3, and it gives that back to me. | 1,025.24 | 5.129 |
If, instead, I said select * from
flights where origin= "New York," | 1,030.369 | 3.901 |
I can see that I don't just need
to filter on the primary key-- | 1,034.27 | 2.79 |
the id-- I can also filter
on any other column. | 1,037.06 | 2.61 |
I can say, give me all the flights
where New York is the origin. | 1,039.67 | 3.25 |
So all the flights
leaving from New York. | 1,042.92 | 2.054 |
You might imagine that
in New York's airport, | 1,044.974 | 1.875 |
for example they likely want
some sort of query that's | 1,046.849 | 2.721 |
going to find all the flights
leaving from New York such | 1,049.57 | 2.43 |
that they can display on a screen
of some sort all of the departures | 1,052 | 3.48 |
from that particular airport. | 1,055.48 | 1.29 |
So you could run a query
like this and get back | 1,056.77 | 2.28 |
only the rows in this database, inside
of this table, that happened to have | 1,059.05 | 4.08 |
an origin of New York, for example. | 1,063.13 | 3.19 |
So let's go ahead and take a
look at how we might actually | 1,066.32 | 2.78 |
run some of these queries
inside of a SQL database. | 1,069.1 | 4.21 |
So in order to create a SQLite
database, which is really just a file, | 1,073.31 | 3.75 |
I can start just by creating the file. | 1,077.06 | 2.18 |
It turns out that in the terminal,
there is a command called Touch that | 1,079.24 | 3.18 |
will create a brand new file for me. | 1,082.42 | 2.19 |
So I'm going to create a
file called flights.sql. | 1,084.61 | 4.04 |
It's going to be a SQLite database
file that by default has nothing in it. | 1,088.65 | 4.03 |
But then, assuming you
have SQLite installed, | 1,092.68 | 2.46 |
I can run SQLite 3
followed by flights.sql, | 1,095.14 | 5.01 |
and now I'm inside of the SQLite prompt. | 1,100.15 | 2.55 |
I can now begin to write commands that
will be executed on this SQL database. | 1,102.7 | 5.53 |
So one thing I might do is
create a table called "flights." | 1,108.23 | 4.14 |
In this table, I want to have an
id column, which is an integer. | 1,112.37 | 4.29 |
It should be the primary key, the main
way via which I identify a flight. | 1,116.66 | 3.59 |
I would like to autoincrement it. | 1,120.25 | 2.643 |
I would also like for the flights
table to have an origin, which | 1,122.893 | 2.667 |
will be a text field that is not null. | 1,125.56 | 2.63 |
I'll add a destination field, also
a text field that is not null. | 1,128.19 | 4.3 |
And then finally I'll
add a duration field, | 1,132.49 | 2.16 |
which is an integer that
also shouldn't be null. | 1,134.65 | 2.76 |
I'll end with an end parentheses
and a semicolon, press Return, | 1,137.41 | 3.42 |
and that executes that
command on my database. | 1,140.83 | 2.61 |
I have now created a
table called "flights." | 1,143.44 | 2.82 |
To verify this in SQLite, in
the prompt I can type .tables, | 1,146.26 | 3.89 |
and that will show me all of the tables
that currently exist in my database. | 1,150.15 | 4.06 |
It just so happens that I
have a table called "flights." | 1,154.21 | 3.125 |
Of course, there's nothing
inside this table, which | 1,157.335 | 2.125 |
I can verify by running
SELECT * from flights, | 1,159.46 | 3.02 |
meaning get all the data
from the flights table. | 1,162.48 | 2.65 |
If I press Return nothing happens. | 1,165.13 | 2.01 |
I don't see anything. | 1,167.14 | 1.05 |
There is no data that
happens to be here. | 1,168.19 | 2.55 |
But now I could say something
like INSERT into Flights. | 1,170.74 | 3.613 |
Then I'll provide in parentheses
the names of the columns. | 1,174.353 | 2.417 |
And on the slide a moment ago I
showed this on multiple lines. | 1,176.77 | 2.618 |
That was just for visuals sake. | 1,179.388 | 1.292 |
These commands can be entirely on
one line if we would like it to. | 1,180.68 | 2.98 |
So I can say origin, destination,
and duration and then provide values. | 1,183.66 | 4.87 |
I can say let's add New
York to London, and I'd | 1,188.53 | 4.01 |
like for this flight to be
duration of 415 minutes. | 1,192.54 | 4.03 |
So I type in the command, press Return. | 1,196.57 | 2.03 |
That adds a new row to my flights table. | 1,198.6 | 3.03 |
I can verify this by running
SELECT * from flights. | 1,201.63 | 4.62 |
And I see that now I have
this table whose id is one-- | 1,206.25 | 3.09 |
that's the id column
from New York to London-- | 1,209.34 | 3.51 |
with a duration of 415 minutes. | 1,212.85 | 2.46 |
I could do this again and again. | 1,215.31 | 1.46 |
I, in advance, prepared
a couple of INSERT | 1,216.77 | 1.75 |
queries just to give us
a little bit more data. | 1,218.52 | 2.34 |
Each of this is just a
different INSERT query | 1,220.86 | 2.74 |
that's going to add one new
flight into our database. | 1,223.6 | 2.94 |
So I'll go ahead and copy those
and then into the database | 1,226.54 | 2.72 |
I'll go ahead and paste in
all these INSERT commands | 1,229.26 | 2.31 |
to insert a whole bunch of
flights into this database. | 1,231.57 | 3.36 |
Now if I run SELECT * from flights
what I get is all of the flights. | 1,234.93 | 5.49 |
This is not formatted
particularly nicely. | 1,240.42 | 1.94 |
SQLite has some additional tricks if
you'd like to format it a little nicer. | 1,242.36 | 3.23 |
So I can say, go ahead and
put this into columns mode, | 1,245.59 | 3.32 |
and it gives me some headers. | 1,248.91 | 2.28 |
So .headers yes. | 1,251.19 | 3.03 |
And now if I SELECT *
from flights, the data | 1,254.22 | 2.74 |
is organized a little more nicely
where things are really into columns | 1,256.96 | 2.93 |
and there are headers
for each of the rows. | 1,259.89 | 1.792 |
Where I can see that I kind have a
text-based representation of what | 1,261.682 | 3.748 |
I was displaying
graphically a moment ago. | 1,265.43 | 1.75 |
That inside of my flights table I have
four columns-- an id column, origin, | 1,267.18 | 4.24 |
destination, and duration. | 1,271.42 | 1.67 |
Each flight is just one of the
rows that's inside of this table. | 1,273.09 | 5.22 |
Now I can begin to run
additional SELECT queries. | 1,278.31 | 2.62 |
If I want to do something like SELECT *
from flights where origin= "New York," | 1,280.93 | 7.19 |
well then instead of getting
back all of the flights, | 1,288.12 | 2.61 |
I'm only going to get back the
flights where the origin is New York. | 1,290.73 | 2.97 |
So I can very quickly
filter down on this data, | 1,293.7 | 2.64 |
only getting the information that I
actually care about taking a look at. | 1,296.34 | 3.45 |
There are other ways of
interacting with SQLite as well, | 1,299.79 | 2.43 |
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