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All right.

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So we're moving on to logical or which, as I just mentioned, is like the brother or sister to logical.

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And and if you've worked with any programming language you're most likely familiar with and and or logical

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and and logical or so logical or you can either write out as or or just like we could write a and for

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and or we can use these to pipe symbols.

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So these are not uppercase I's or L's or ones.

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They are the pipe character which is usually located above the right return or enter key.

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You have to hit shift most often to hit it.

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So it's two of them together, just like it was to Ampersand four.

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And it's just symbols.

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It's pretty standard.

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Rights are very standardized across all programming languages that I've worked in ampersand for and

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pipes for or but you can also use the phonetic or the spelled out version or so.

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Before we dive into exactly how it works, let's try something.

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So we had this in the last video.

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This selects all books written by Dave Eggers, released after the year 2010.

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But what if we just change the ampersand to the or pipes?

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What do you think will happen, first of all?

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So I'm just going to copy this so we don't have to type this all again.

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And just change the ampersand here to or and I'll make I'll hit return so it's clearer what's happening.

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So if we read this, if you just say the word or here it makes a bit more sense.

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Select title and author name and release here from books where author name is Eggers or released your

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is greater than 2010.

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So if we run it, what we'll get is all books written by Dave Eggers and all books where a release year

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is greater than 2010.

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So rather than both sides of this having to be true, just if either side is true, we'll get the data.

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So we get all the books by Eggers, including this one.

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Our heartbreaking work is Staggering Genius, which came before 2010.

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But then we move on to the second part, which MySQL selected all books that were released after 2010,

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regardless of the author name.

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So it's a way for us to specify two things, either of which we want to be true or both.

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So in the case of a hologram for the King, it is both written by Dave Eggers, and it was released

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after 2010.

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Or same thing with the circle here.

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But 10% happier, for instance, was only this part was true.

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Released year is greater than 2010 because author L name is Harris or Saunders in this case or Gaiman.

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So again, that symbol right there, I forgot I made this nice little slide with this animation that

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change a symbol is very, very important.

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It changes the meaning entirely from the statement.

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Okay.

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So if we have two conditions with an ampersand between them or three or any number of conditions with

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ampersand, it means that both sides must be true in order for the whole thing to be true, as we've

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seen already.

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However, with the OR operator, it means only one side must be true for the whole thing to be true,

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or both sides can be true as well.

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And I know that's a bit odd to talk about in this way without actual examples.

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So if we hop over again, I'm going to do the same thing I've been doing the last couple of videos.

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I'm going to type up a few example exercises and then we'll go over solutions.

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Okay, so I'm back here.

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I've got three, just three this time that I'll use logical or so try them out and then I'll be right

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back with a solution and I'm back already.

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Okay, so first one here.

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40 less than or equal to 100.

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Well, that part's true.

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40 is less than 100.

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So it doesn't matter what's over here.

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This whole thing is true because we only need one half to be true.

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It happens that negative two is not greater than zero, but that's irrelevant because the left side

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is true.

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Moving on to this one, ten greater than five, is that true?

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Yes.

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So it doesn't matter what's on the right side, but that happens to also be true.

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So the whole thing is true.

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So we get one and this last one, a bit of a curveball.

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Is the letter a equal to the number five?

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Well, that's not true.

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However, this side says 3000 is greater than 2000.

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That is true.

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So the whole thing is true.

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As you can see, we get one for true.

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Last thing before I forget just like with and we can chain or together as many times as we want so it

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doesn't have to be something like this.

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So if I go back to this example, select title, author l name or here from books where author name

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is Eggers or released year is greater than 2010.

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So let's try adding an OR here and I'll spell it out this time.

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And let's say not only do we care or do we want to select things written by Eggers or released year

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greater than 2010, we'll also add another or which is stock quantity is greater than 100 so books that

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we have a lot of stock in as well.

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And let's also print stock quantity just like that.

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Just copy this whole thing, paste it semicolon.

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And if we look see it makes a slight difference because we also get this David Foster Wallace story

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collection in here, which is written in 2004, which normally wouldn't make the cut with our previous

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version, but because we added stock quantity greater than 100, it's in here because stock quantity

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is greater than 172.

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So for some of these, for instance, a hologram for the King, all three parts are true.

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It's written by Eggers.

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It's released after 2010, and it has more than 100 copies in stock.

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But then, like for David Foster Wallace and Oblivion, only one part is true.

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The last part.

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So just goes to show you that only one component, even if we have three different conditions, only

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one part has to be true for the entire thing to be true and for it to be selected and spit back to us.

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Okay.

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So that's logical.

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Or one thing that I will point out that I know you're probably dying to get on with this video, but

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you can combine or and end and we'll see how to do that in a little bit.