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

text stringlengths 1 81	start float64 0 10.1k	duration float64 0 24.9
and now I can end that particular statement	5,531.07	2.93
I want to run after I hear a delete on collections.	5,534	4.11
So I'll hit Enter now, and let me type dot schema.	5,538.11	3.66
I can actually see this trigger is part of my schema.	5,541.77	4.71
I can see create trigger sell before delete on transactions	5,546.48	3.33
underneath the transactions table.	5,549.81	3.6
OK, let's try putting this into action here.	5,553.41	3.27
Let me try actually deleting something from our collections table.	5,556.68	2.79
I'll say delete from collections where the title equals	5,559.47	4.62
"Profusion of Flowers."	5,564.09	1.83
I want to sell this particular piece of artwork from our collection.	5,565.92	3.54
I'll hit semicolon here, and now nothing seems to happen as usual,	5,569.46	5.07
but if I select star from collections--	5,574.53	3.76
from collections, I see that piece is gone.	5,578.29	4.53
It's no longer in here, and if I select star from transactions--	5,582.82	5.25
select star from transactions, I actually see it's been sold.	5,588.07	4.65
So automatically, I added "Profusion of Flowers"	5,592.72	3.12
with the action of sold to my transactions table.	5,595.84	2.97
I did not type insert myself.	5,598.81	2.59
I instead created a trigger to run this statement,	5,601.4	3.56
insert into, whenever I delete it on collections.	5,604.96	4.76
Let's try one more.	5,609.72	1.29
We want to not just be able to sell artwork,	5,611.01	1.89
but also add it to our collection by buying it.	5,612.9	3.36
So I create a trigger called buy.	5,616.26	2.79
Let me type create trigger "buy," and now I	5,619.05	5.7
want to run this statement forthcoming after an insert on collections.	5,624.75	7.71
So I want to first insert a new item to collections, and when I do, after I do,	5,632.46	6.36
I want to run this query coming next.	5,638.82	2.79
Now, I want to, for each row, begin the statement I want to run.	5,641.61	5.98
So as we said before, I want to insert into the transactions table.	5,647.59	4.79
I want to insert into the title and action columns, just like this.	5,652.38	5.71
Now, I want to insert some values.	5,658.09	3.29
The values I want to insert--	5,661.38	1.68
well, I want to insert the new title, the new row I've just added.	5,663.06	4.35
So in addition to old, we also have new when	5,667.41	3.33
I'm talking when I'm using a trigger on an insert.	5,670.74	2.58
So I'll say new.title, where again, new is the new row or rows I'm inserting,	5,673.32	6.78
and the dot title is a column called title.	5,680.1	4.83
Now, here I'll say the action was bought.	5,684.93	2.43
We bought this artwork.	5,687.36	1.71
I'll hit semicolon here, and now, I'll say end	5,689.07	3.18
to say this is the end of my statement I want to run for every row I	5,692.25	4.26
insert on collections.	5,696.51	2.07
Let me hit Enter here.	5,698.58	1.62
I've created this trigger.	5,700.2	1.32
I can type dot schema to see it in my actual schema.	5,701.52	4.66
Now, let's try inserting.	5,706.18	1.73
I'll say insert into collections.	5,707.91	3.72
I want to insert into the title and accession number,	5,711.63	4.05
as well as the acquired columns here.	5,715.68	3.27
I want to insert some new artwork.	5,718.95	2.31
Maybe I sold Profusion of Flowers, but now I want to just buy it back.	5,721.26	3.37
So I'll say I'll insert "Profusion of Flowers" is the title.	5,724.63	5.88
The accession number was 56.257, and the date we acquired it, well,	5,730.51	6.65
that was in 1956/04/12.	5,737.16	4.2
Let's hit semicolon here.	5,741.36	1.95
Now, I'll insert, and I'll say select star from collections.	5,743.31	5.46
I should see Profusion of Flowers back in my table.	5,748.77	4.54
Now though, if I say select star from transactions--	5,753.31	3.47
select star from transactions, I should see	5,756.78	3.24
I previously sold Profusion of Flowers, and later bought it back.	5,760.02	3.96
So again, I didn't run this insert myself.	5,763.98	4.06
I instead triggered it by making my very own insert on the collections table.	5,768.04	6.12
So this is the power of triggers.	5,774.16	2.27
You're able to run statements that I myself	5,776.43	2.4
didn't create in response to statements that I actually did.	5,778.83	4.2
So let me ask here, what questions do we have on these triggers	5,783.03	4.41
and what they can do for us?	5,787.44	1.56
Let's go to Simon.	5,791.65	1.58
SIMON: I'd like to know if there are only--	5,793.23	5.16
there is only one SQL inquiry that you can write	5,798.39	4.05
in a trigger or multiple inquiries.	5,802.44	3.73
SPEAKER: Yeah, we saw begin and end in our triggers	5,806.17	3.53
here, where begin indicates the start of our statement,	5,809.7	2.59
and end indicates the end.	5,812.29	1.73
You actually can have multiple statements	5,814.02	2.46
inside of the begin and end separated by,	5,816.48	2.97
of course, that usual semicolon that we have.	5,819.45	3.68
OK, so one final idea here that we're getting at-- we're	5,823.13	3.9
kind of touching at with this transactions table is	5,827.03	2.34
this idea of having a soft deletion.	5,829.37	3.33
So when I dropped something from my collections table,	5,832.7	4.68
it actually ended up in my transactions table,	5,837.38	3.51
so it wasn't fully deleted in the sense that I'm keeping a record of it	5,840.89	3.6
somewhere else.	5,844.49	1.84
There's also one more way among many others	5,846.33	2.6
to implement this idea of soft deletions, that is not quite fully	5,848.93	3.193
deleting something from my database but instead keeping it	5,852.123	2.417
around with a log that we've removed it in some way.	5,854.54	3.43
Let's look at this table here.	5,857.97	1.97
I have collections, but I also have this column called "deleted,"	5,859.94	5.31
and by default, the value here will be 0.	5,865.25	3.75
That is, by default, I'll add some artwork to my collections table	5,869	5.19
and deleted will be 0.	5,874.19	2.79
If I want to delete a piece of artwork though, what could I do?	5,876.98	4.23
Instead of deleting it fully from my table or removing the row,	5,881.21	3.84
I could mark it as deleted.	5,885.05	2.04
I could change the deleted column from a 0 to a 1.	5,887.09	3.54
Let's say I wanted to delete Farmers Working At Dawn	5,890.63	2.64

and now I can end that particular statement

5,531.07

2.93

I want to run after I hear a delete on collections.

5,534

4.11

So I'll hit Enter now, and let me type dot schema.

5,538.11

3.66

I can actually see this trigger is part of my schema.

5,541.77

4.71

I can see create trigger sell before delete on transactions

5,546.48

3.33

underneath the transactions table.

5,549.81

3.6

OK, let's try putting this into action here.

5,553.41

3.27

Let me try actually deleting something from our collections table.

5,556.68

2.79

I'll say delete from collections where the title equals

5,559.47

4.62

"Profusion of Flowers."

5,564.09

1.83

I want to sell this particular piece of artwork from our collection.

5,565.92

3.54

I'll hit semicolon here, and now nothing seems to happen as usual,

5,569.46

5.07

but if I select star from collections--

5,574.53

3.76

from collections, I see that piece is gone.

5,578.29

4.53

It's no longer in here, and if I select star from transactions--

5,582.82

5.25

select star from transactions, I actually see it's been sold.

5,588.07

4.65

So automatically, I added "Profusion of Flowers"

5,592.72

3.12

with the action of sold to my transactions table.

5,595.84

2.97

I did not type insert myself.

5,598.81

2.59

I instead created a trigger to run this statement,

5,601.4

3.56

insert into, whenever I delete it on collections.

5,604.96

4.76

Let's try one more.

5,609.72

1.29

We want to not just be able to sell artwork,

5,611.01

1.89

but also add it to our collection by buying it.

5,612.9

3.36

So I create a trigger called buy.

5,616.26

2.79

Let me type create trigger "buy," and now I

5,619.05

5.7

want to run this statement forthcoming after an insert on collections.

5,624.75

7.71

So I want to first insert a new item to collections, and when I do, after I do,

5,632.46

6.36

I want to run this query coming next.

5,638.82

2.79

Now, I want to, for each row, begin the statement I want to run.

5,641.61

5.98

So as we said before, I want to insert into the transactions table.

5,647.59

4.79

I want to insert into the title and action columns, just like this.

5,652.38

5.71

Now, I want to insert some values.

5,658.09

3.29

The values I want to insert--

5,661.38

1.68

well, I want to insert the new title, the new row I've just added.

5,663.06

4.35

So in addition to old, we also have new when

5,667.41

3.33

I'm talking when I'm using a trigger on an insert.

5,670.74

2.58

So I'll say new.title, where again, new is the new row or rows I'm inserting,

5,673.32

6.78

and the dot title is a column called title.

5,680.1

4.83

Now, here I'll say the action was bought.

5,684.93

2.43

We bought this artwork.

5,687.36

1.71

I'll hit semicolon here, and now, I'll say end

5,689.07

3.18

to say this is the end of my statement I want to run for every row I

5,692.25

4.26

insert on collections.

5,696.51

2.07

Let me hit Enter here.

5,698.58

1.62

I've created this trigger.

5,700.2

1.32

I can type dot schema to see it in my actual schema.

5,701.52

4.66

Now, let's try inserting.

5,706.18

1.73

I'll say insert into collections.

5,707.91

3.72

I want to insert into the title and accession number,

5,711.63

4.05

as well as the acquired columns here.

5,715.68

3.27

I want to insert some new artwork.

5,718.95

2.31

Maybe I sold Profusion of Flowers, but now I want to just buy it back.

5,721.26

3.37

So I'll say I'll insert "Profusion of Flowers" is the title.

5,724.63

5.88

The accession number was 56.257, and the date we acquired it, well,

5,730.51

6.65

that was in 1956/04/12.

5,737.16

4.2

Let's hit semicolon here.

5,741.36

1.95

Now, I'll insert, and I'll say select star from collections.

5,743.31

5.46

I should see Profusion of Flowers back in my table.

5,748.77

4.54

Now though, if I say select star from transactions--

5,753.31

3.47

select star from transactions, I should see

5,756.78

3.24

I previously sold Profusion of Flowers, and later bought it back.

5,760.02

3.96

So again, I didn't run this insert myself.

5,763.98

4.06

I instead triggered it by making my very own insert on the collections table.

5,768.04

6.12

So this is the power of triggers.

5,774.16

2.27

You're able to run statements that I myself

5,776.43

2.4

didn't create in response to statements that I actually did.

5,778.83

4.2

So let me ask here, what questions do we have on these triggers

5,783.03

4.41

and what they can do for us?

5,787.44

1.56

Let's go to Simon.

5,791.65

1.58

SIMON: I'd like to know if there are only--

5,793.23

5.16

there is only one SQL inquiry that you can write

5,798.39

4.05

in a trigger or multiple inquiries.

5,802.44

3.73

SPEAKER: Yeah, we saw begin and end in our triggers

5,806.17

3.53

here, where begin indicates the start of our statement,

5,809.7

2.59

and end indicates the end.

5,812.29

1.73

You actually can have multiple statements

5,814.02

2.46

inside of the begin and end separated by,

5,816.48

2.97

of course, that usual semicolon that we have.

5,819.45

3.68

OK, so one final idea here that we're getting at-- we're

5,823.13

3.9

kind of touching at with this transactions table is

5,827.03

2.34

this idea of having a soft deletion.

5,829.37

3.33

So when I dropped something from my collections table,

5,832.7

4.68

it actually ended up in my transactions table,

5,837.38

3.51

so it wasn't fully deleted in the sense that I'm keeping a record of it

5,840.89

3.6

somewhere else.

5,844.49

1.84

There's also one more way among many others

5,846.33

2.6

to implement this idea of soft deletions, that is not quite fully

5,848.93

3.193

deleting something from my database but instead keeping it

5,852.123

2.417

around with a log that we've removed it in some way.

5,854.54

3.43

Let's look at this table here.

5,857.97

1.97

I have collections, but I also have this column called "deleted,"

5,859.94

5.31

and by default, the value here will be 0.

5,865.25

3.75

That is, by default, I'll add some artwork to my collections table

5,869

5.19

and deleted will be 0.

5,874.19

2.79

If I want to delete a piece of artwork though, what could I do?

5,876.98

4.23

Instead of deleting it fully from my table or removing the row,

5,881.21

3.84

I could mark it as deleted.

5,885.05

2.04

I could change the deleted column from a 0 to a 1.

5,887.09

3.54

Let's say I wanted to delete Farmers Working At Dawn

5,890.63

2.64