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24.9
In this case, I'll use the let's say [? collections' ?] [? name, ?] DELETE
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5.13
FROM "collections."
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1.92
But I don't want to do this.
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1.3
I don't want to say DELETE FROM "collections"
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semicolon end of statement, because then I'll delete every row.
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5.19
What I should instead do is this.
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DELETE FROM "collections" WHERE some condition is true.
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4.05
Maybe the title in this case is a title I'm trying to remove.
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So I'll say "title" equals "Spring outing," just like this, semicolon,
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6.06
Enter.
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1.08
Now, nothing seems to happen.
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1.23
But if I do SELECT [? star ?] FROM "collections" semicolon,
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5.4
we no longer see Spring outing.
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2.28
And notice here, how the id column, the id of 3 is now gone.
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5.16
If I were to insert some new row here, I would start over
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3.3
with the highest number, which is 7 in this case, going from 7 to 8.
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4.23
But 3 is no longer part of our database.
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4.04
Let me try this again, notice how this one called Imaginative Landscape,
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4.02
the acquired date is NULL.
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1.77
We don't know when we got it.
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1.873
Well, let's say that we eventually sell.
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1.667
It's no longer part of our database.
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1.53
We could use a condition based on NULL to remove this particular artwork.
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4.8
So I'll say this.
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1
Let me try to DELETE FROM "collections" WHERE "title" equals--
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5.96
not Spring outing, but WHERE the acquired date-- sorry,
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the "acquired" date IS NULL semicolon.
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I could also use is NOT NULL--
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3.01
WHERE "acquired" IS NOT NULL, but that would delete all the pieces of artwork
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that actually have an acquired date.
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2.16
Here, I want to leave only those that do not have an acquired date.
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3.75
So I'll say where "acquired" IS NULL.
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3.51
Now, I'll hit Enter, nothing seems to happen,
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2.55
but I'll say Select [? star ?] FROM "collections" semicolon.
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4.53
And I'll see that piece of artwork is now gone.
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4.17
I only have those that have an acquired date.
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4.8
OK, so similar to [? INSERT, ?] we've been able to [? delete ?] one row
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6.06
at a time.
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1.11
But it would probably be helpful for us to delete multiple rows at a time
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4.38
as well.
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1.18
Let's look again at our table.
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1.91
Here we have our artwork, as it currently stands, and maybe
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4.74
let's say we want to delete those pieces that we acquired before 1909.
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5.82
Here in Boston, the MFA actually moved locations in 1909 to a new place
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still in Boston, but a brand new building altogether.
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2.8
So let's say that perhaps they left some items at their old location,
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they're no longer part of their collections.
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2.67
Via what condition do you think could I select these three rows from
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7.16
my [? DELETE ?] [? FROM? ?] What could I put in my condition to delete these
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three rows?
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1.23
Let me ask the audience here.
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What might you propose for [? delete ?] [? from ?] here to delete those three
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particular rows?
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0.795
Let's go to [? Shiv. ?]
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1.11
SPEAKER 9: Greater than [? 5. ?] [? id ?] equals greater than 5.
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SPEAKER 1: That's a good observation.
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So we could look at our table here.
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1.458
We see the id could be greater than or equal to 5, that would
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remove these three rows certainly.
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2.73
There's probably another way to do this too.
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2.16
Any other ideas besides the id, what else can we use?
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3.81
Let's go to [? Yasavi. ?]
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1.85
SPEAKER 10: So we could compare the dates and use greater than or less
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than sign with the acquired dates.
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3.27
SPEAKER 1: So you're proposing to use the date column too.
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That makes sense to me as well.
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1.32
We could see acquired here, perhaps we could see,
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is the acquired value less than 1909, that year that we move locations,
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5.8
we could also probably use the title, the [? accession ?] [? number, ?]
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3.41
and so on.
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0.88
And each has their own [? trade-offs. ?]
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2.21
Remember, though, for this particular query, which
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is deleting those items that were part of the museum
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acquired before 1909, probably best to use the acquired
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date to actually delete those rows.
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What if, for instance, our ids are actually not like this.
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But they're kind of interspersed around.
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2.28
I couldn't really do a query like if the id is greater than or equal to 5,
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because I could also include those that were maybe acquired 1911,
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[? 1956, ?] and so on. [? It's ?] [? probably ?] ideal for me to use this
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date if it's the date that I ultimately care about.
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So let's try this.
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1.07
I'll go back to my environment.
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And I'll try to delete these three particular rows.
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I'll try DELETE FROM "collections," as we saw before.
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But now here comes my condition.
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I'll say WHERE the "acquired" column is less than some date that I'll give.
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And here, I'll give 1909-01-01.
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It turns out that SQLite has a few ways to represent dates.
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One of which is this format that follows the YYYY or the year,
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5.04
four digits, and then dash, and then MM or the month with two digits,
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and then dash again, DD, in this case, the day in two digits.
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So 1909-01-01 means January 1st, 1909.
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And I can use these same operators with dates.
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I could say greater than, or less than, or equal to this particular date.
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And SQLite will be able to parse this for me to understand what I mean,
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which is earlier than 1909.
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3.63
So let's try this then.
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1.32
I'll hit Enter, and nothing seems to happen.
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3.12
But if I do SELECT [? star ?] FROM "collections,"
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