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Well, for that, we could use this next SQL keyword, this one called WHERE.
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So WHERE allows me to get back not all rows, but only
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some rows where some condition is true.
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So WHERE is often combined with other conditions
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to make sure I only get back some rows, where that condition is true.
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Let's try looking at that in SQLite to get
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a feel for what it can do for us here.
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So I'll go back to my WHERE.
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And I will then go back to SQLite here.
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Hit Control-L to clear my terminal.
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And I'll then try this query.
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I'll say SELECT "title."
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SELECT "title."
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And why don't we also select author along the way?
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Two columns here.
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And I'll select them from my longlist table.
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But I don't want all rows.
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I only want, let's say, those titles and authors that were longlisted in 2023.
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So I'll do this.
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I'll say WHERE the "year" column is equal to 2023.
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And notice here how 2023 is not in quotes because it
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is an actual number, an integer.
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So I don't need to quote it like I would a string some collection of characters
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or a table or column name.
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So I'll hit Enter here.
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And what do I see?
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Well, I see only those books that were nominated in 2023.
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Let's try this again.
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I might try not just 2023--
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I might try 2022 like this.
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Hit Semicolon.
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Now, I'll see those books nominated in 2022.
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I could keep going.
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I could say why not 2022?
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Why not 2021?
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Now, I have all those books nominated in 2021.
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So this is handy.
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We can set things equal to or not equal to make some condition here.
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And we also have others we could use.
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We saw equals just now.
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But we similarly have not equals.
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And we have this kind of obscure operator down here.
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This one being also equivalent to not equals as we'll see in just a minute.
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But let me first ask now, what questions do
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we have on how to use WHERE or using SELECT so far?
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SPEAKER: Why are the subsets of SQL?
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CARTER ZENKE: A good question.
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Are there subsets of SQL?
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So there are.
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In fact, S-Q-L or SQL was defined by the,
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I believe it's the ANSI, like standard corporation.
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They have a whole set of the SQL language
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that is like the official version of it.
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You might be able to use some subset of that version
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with the database manager system that you actually use.
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So for SQLite, we're using a subset of SQL that works with SQLite.
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Similarly, if you were using another software like PostgreSQL or MySQL,
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you could use another subset there too.
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Let's take another question from Tayas, perhaps.
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SPEAKER: Then I want to know that, can we add 2022 and 2021 in a terminal?
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CARTER ZENKE: Yeah, good question.
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Could I, perhaps, try to filter by 2021 and 2022?
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I could do that.
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And we'll see that in just a moment here.
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So let's keep going and exploring some other options with not equals.
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And then we'll see how we can combine conditions using WHERE too.
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So let's go back, and let's focus first on trying
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to use these not equal operators.
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We saw the exclamation point equals and this greater than, less than sign put
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together.
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So let's try a few of those.
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Let's say I want to find books that are written by a certain author.
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Well, I could use equals for that.
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But let's say I also want to find books that are not
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written in the hardcover format, like they
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tend to be more expensive and so on.
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So I don't want hardcover books.
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Well, I could try a query like this.
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I could say SELECT "title" and "format," where format is either hardcover
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or paperback, FROM my "longlist" table.
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And now I'll say, WHERE the "format" is not equal to hardcover Semicolon.
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So notice here I'm using single quotes for hardcover.
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This is a string.
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It's not a table name or a column name.
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It is just a string.
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So I'm using single quotes here.
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Everything else, though, like format, longlist, title, et cetera,
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those are all table names or column names.
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So again, I'll hit Enter.
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And now I'll see that these are all in paperback according to my table.
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I've omitted those that are hardcover.
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Well, I could also use in this case, the greater than or less
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than sign put together to say not equals as well.
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Let me just hit the Up Arrow on my computer
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to reveal what I just previously typed.
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I'll then tab back over and say not exclamation point equals, but less than
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and then greater than.
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Hit Enter now.
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And I should see the very same results.
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But all I did was change this operator from exclamation point
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