pre-view/CS50-raw · Datasets at Hugging Face

text stringlengths 1 81	start float64 0 10.1k	duration float64 0 24.9
as sold all automatically.	5,164.37	3.88
Let's think to maybe the museum acquires some piece of artwork.	5,168.25	4.07
Maybe they actually add something new to their collection.	5,172.32	3.12
We want that to show up in our transactions as well with the action of	5,175.44	4.44
bought.	5,179.88	0.69
Well, let's try it.	5,180.57	0.87
I could probably add a new row here.	5,181.44	2.05
I could say let's add "Peonies and Butterfly" to my collection here.	5,183.49	4.79
Now, if I have the appropriate trigger, I	5,188.28	3.42
could run an insert into on transactions automatically	5,191.7	4.62
that would insert this same title with the action of bot,	5,196.32	3.87
thereby keeping a log of all of our sold pieces of artwork and all of our	5,200.19	4.92
bought pieces of artwork.	5,205.11	2.25
Now to create what we're calling a trigger here,	5,207.36	2.64
we can use the following syntax.	5,210	2.43
I could say first create trigger, and then some name.	5,212.43	5.19
So I tend to give triggers names to identify them	5,217.62	2.64
among all of my database [INAUDIBLE],, like my tables and so on.	5,220.26	4.41
Here, after I say create trigger, I have to specify.	5,224.67	4.17
Should this trigger, this statement, run after or before some other SQL	5,228.84	6.24
statement?	5,235.08	1.11
Let's keep going with before here.	5,236.19	2.16
Maybe it runs before an insert on some table.	5,238.35	4.5
That's fine.	5,242.85	1.11
It could also run before an update of a column on some table.	5,243.96	5.23
It could even run before a delete on some table, and keep in mind,	5,249.19	5
this could be before or after any of these kinds of SQL statements.	5,254.19	4.26
In this case, we have insert, update, and delete.	5,258.45	4.32
Now after we say this, what we should say, too, is for each row.	5,262.77	5.28
For each row means that if I were to maybe delete multiple rows,	5,268.05	5.16
I should run my SQL statement for each row that I delete.	5,273.21	4.2
If I delete two rows, I should run this statement coming soon two times.	5,277.41	6.57
OK, so now we've set up our trigger, at least kind of the data, the setup	5,283.98	5.49
for it here.	5,289.47	1.08
What we haven't done yet is specify what statement should run whenever	5,290.55	5.07
we see a delete on particular table.	5,295.62	2.4
Well, let's try this.	5,298.02	1.62
Here I could say begin.	5,299.64	1.95
Begin means here comes my statement I want to run	5,301.59	3.27
whenever I hear a delete on this table.	5,304.86	3.51
Now, all right.	5,308.37	1.47
That query down below.	5,309.84	1.59
That statement inside my begin, and I'll finish it off	5,311.43	3.27
with an end to say this is the end of my statement,	5,314.7	3.21
and my entire trigger looks like all of this lines of code here	5,317.91	3.69
to say listen for a delete and run this statement in here for each row	5,321.6	5.61
that I delete, or update, or insert.	5,327.21	3.32
So let's try actually implementing in this case	5,330.53	3.37
the museum's collections where they're trying to sell or buy	5,333.9	3.56
pieces of artwork, and automatically add them	5,337.46	2.34
to their transaction table whenever they create or delete some piece of data	5,339.8	3.96
from their collections.	5,343.76	1.95
Go back to my terminal here, and let me pull up a database.	5,345.71	4.59
I'll do SQLite 3 mfa.db, and you'll notice	5,350.3	3.96
that this is the same schema that we've had before.	5,354.26	3.12
We have collections, artists, and the created table.	5,357.38	4.11
What's missing here, though, is our transactions table.	5,361.49	3.13
So let me make that for us here.	5,364.62	1.91
I'll say let me go create table, transactions,	5,366.53	4.05
and now let me give it an ID column of type integer.	5,370.58	5.42
Now, I'll also give it a title column as we saw before called "Text."	5,376	5.03
It's in this column [INAUDIBLE],, the title	5,381.03	2.28
of the piece we either bought or sold.	5,383.31	2.79
Now, let me also include the action column, also of type text	5,386.1	4.86
to say whether we bought or sold this piece.	5,390.96	4.25
OK, finally, I'll make the ID column my primary key.	5,395.21	4.84
And if I say semicolon here and hit Enter, I now have created this table.	5,400.05	6.03
So if I say dot schema, notice how I can now see my transactions	5,406.08	4.13
table down below, and I'm safe to run insert	5,410.21	3.78
on this table to add some data to it.	5,413.99	4.11
Well, let's try now creating our very first trigger.	5,418.1	3.39
We're going to try to create a trigger that whenever an item is deleted	5,421.49	3.81
from our collections table, we actually add it to our transactions table	5,425.3	3.69
with the action of sold, meaning we sold this particular item.	5,428.99	4.21
So let me say create trigger, as we saw before,	5,433.2	3.35
and give it some name to identify it.	5,436.55	2.28
I'll call this one sell.	5,438.83	2.2
Now, I'll say I want to run this trigger before I delete on the collections	5,441.03	6.26
table.	5,447.29	0.88
So before I run the delete query on my collections table,	5,448.17	4.7
I want to run this statement instead.	5,452.87	4.11
I'll say for each row, begin.	5,456.98	3.85
I want to now give you some statement to run for each row	5,460.83	3.35
that I delete from collections.	5,464.18	2.55
Let's make it this query here.	5,466.73	1.62
On 1, 2, 3, 4 spaces to indent and make sure	5,468.35	3.81
this is clearly the query I want to run after I run the delete on collections.	5,472.16	6.69
I'll say I want to insert into transactions.	5,478.85	4.17
I want to insert into the title and action columns.	5,483.02	4.71
What value should I insert?	5,487.73	1.68
Well, I should insert the old title, and actually, in triggers,	5,489.41	4.8
you get access to this keyword called old.	5,494.21	3.12
This is the title that we've just deleted from our collection.	5,497.33	4.27
So old.title gives me access to the old row, the row we deleted,	5,501.6	4.94
its title column in particular.	5,506.54	2.62
Now, let me add in the action, which is just plain and simple "sold."	5,509.16	5.05
So this is the query to run before I delete on collections.	5,514.21	4.61
I will take the title of the row I'm about to delete, and insert it	5,518.82	4.53
into transactions along with the action sold.	5,523.35	3.6
Let me type a semicolon here to say this is my entire query, hit Enter again,	5,526.95	4.12

as sold all automatically.

5,164.37

3.88

Let's think to maybe the museum acquires some piece of artwork.

5,168.25

4.07

Maybe they actually add something new to their collection.

5,172.32

3.12

We want that to show up in our transactions as well with the action of

5,175.44

4.44

bought.

5,179.88

0.69

Well, let's try it.

5,180.57

0.87

I could probably add a new row here.

5,181.44

2.05

I could say let's add "Peonies and Butterfly" to my collection here.

5,183.49

4.79

Now, if I have the appropriate trigger, I

5,188.28

3.42

could run an insert into on transactions automatically

5,191.7

4.62

that would insert this same title with the action of bot,

5,196.32

3.87

thereby keeping a log of all of our sold pieces of artwork and all of our

5,200.19

4.92

bought pieces of artwork.

5,205.11

2.25

Now to create what we're calling a trigger here,

5,207.36

2.64

we can use the following syntax.

5,210

2.43

I could say first create trigger, and then some name.

5,212.43

5.19

So I tend to give triggers names to identify them

5,217.62

2.64

among all of my database [INAUDIBLE],, like my tables and so on.

5,220.26

4.41

Here, after I say create trigger, I have to specify.

5,224.67

4.17

Should this trigger, this statement, run after or before some other SQL

5,228.84

6.24

statement?

5,235.08

1.11

Let's keep going with before here.

5,236.19

2.16

Maybe it runs before an insert on some table.

5,238.35

4.5

That's fine.

5,242.85

1.11

It could also run before an update of a column on some table.

5,243.96

5.23

It could even run before a delete on some table, and keep in mind,

5,249.19

5

this could be before or after any of these kinds of SQL statements.

5,254.19

4.26

In this case, we have insert, update, and delete.

5,258.45

4.32

Now after we say this, what we should say, too, is for each row.

5,262.77

5.28

For each row means that if I were to maybe delete multiple rows,

5,268.05

5.16

I should run my SQL statement for each row that I delete.

5,273.21

4.2

If I delete two rows, I should run this statement coming soon two times.

5,277.41

6.57

OK, so now we've set up our trigger, at least kind of the data, the setup

5,283.98

5.49

for it here.

5,289.47

1.08

What we haven't done yet is specify what statement should run whenever

5,290.55

5.07

we see a delete on particular table.

5,295.62

2.4

Well, let's try this.

5,298.02

1.62

Here I could say begin.

5,299.64

1.95

Begin means here comes my statement I want to run

5,301.59

3.27

whenever I hear a delete on this table.

5,304.86

3.51

Now, all right.

5,308.37

1.47

That query down below.

5,309.84

1.59

That statement inside my begin, and I'll finish it off

5,311.43

3.27

with an end to say this is the end of my statement,

5,314.7

3.21

and my entire trigger looks like all of this lines of code here

5,317.91

3.69

to say listen for a delete and run this statement in here for each row

5,321.6

5.61

that I delete, or update, or insert.

5,327.21

3.32

So let's try actually implementing in this case

5,330.53

3.37

the museum's collections where they're trying to sell or buy

5,333.9

3.56

pieces of artwork, and automatically add them

5,337.46

2.34

to their transaction table whenever they create or delete some piece of data

5,339.8

3.96

from their collections.

5,343.76

1.95

Go back to my terminal here, and let me pull up a database.

5,345.71

4.59

I'll do SQLite 3 mfa.db, and you'll notice

5,350.3

3.96

that this is the same schema that we've had before.

5,354.26

3.12

We have collections, artists, and the created table.

5,357.38

4.11

What's missing here, though, is our transactions table.

5,361.49

3.13

So let me make that for us here.

5,364.62

1.91

I'll say let me go create table, transactions,

5,366.53

4.05

and now let me give it an ID column of type integer.

5,370.58

5.42

Now, I'll also give it a title column as we saw before called "Text."

5,376

5.03

It's in this column [INAUDIBLE],, the title

5,381.03

2.28

of the piece we either bought or sold.

5,383.31

2.79

Now, let me also include the action column, also of type text

5,386.1

4.86

to say whether we bought or sold this piece.

5,390.96

4.25

OK, finally, I'll make the ID column my primary key.

5,395.21

4.84

And if I say semicolon here and hit Enter, I now have created this table.

5,400.05

6.03

So if I say dot schema, notice how I can now see my transactions

5,406.08

4.13

table down below, and I'm safe to run insert

5,410.21

3.78

on this table to add some data to it.

5,413.99

4.11

Well, let's try now creating our very first trigger.

5,418.1

3.39

We're going to try to create a trigger that whenever an item is deleted

5,421.49

3.81

from our collections table, we actually add it to our transactions table

5,425.3

3.69

with the action of sold, meaning we sold this particular item.

5,428.99

4.21

So let me say create trigger, as we saw before,

5,433.2

3.35

and give it some name to identify it.

5,436.55

2.28

I'll call this one sell.

5,438.83

2.2

Now, I'll say I want to run this trigger before I delete on the collections

5,441.03

6.26

table.

5,447.29

0.88

So before I run the delete query on my collections table,

5,448.17

4.7

I want to run this statement instead.

5,452.87

4.11

I'll say for each row, begin.

5,456.98

3.85

I want to now give you some statement to run for each row

5,460.83

3.35

that I delete from collections.

5,464.18

2.55

Let's make it this query here.

5,466.73

1.62

On 1, 2, 3, 4 spaces to indent and make sure

5,468.35

3.81

this is clearly the query I want to run after I run the delete on collections.

5,472.16

6.69

I'll say I want to insert into transactions.

5,478.85

4.17

I want to insert into the title and action columns.

5,483.02

4.71

What value should I insert?

5,487.73

1.68

Well, I should insert the old title, and actually, in triggers,

5,489.41

4.8

you get access to this keyword called old.

5,494.21

3.12

This is the title that we've just deleted from our collection.

5,497.33

4.27

So old.title gives me access to the old row, the row we deleted,

5,501.6

4.94

its title column in particular.

5,506.54

2.62

Now, let me add in the action, which is just plain and simple "sold."

5,509.16

5.05

So this is the query to run before I delete on collections.

5,514.21

4.61

I will take the title of the row I'm about to delete, and insert it

5,518.82

4.53

into transactions along with the action sold.

5,523.35

3.6

Let me type a semicolon here to say this is my entire query, hit Enter again,

5,526.95

4.12