When we talk about the joins, notice the numbers
at the bottom.
I told you the magic number was 240.
If you want nothing to change in your primary table,
your anchor table-- for us, that was ZVIBERMESSAGE.
We wanted to keep 240 messages.
You'll do a LEFT JOIN.
What that means is you are saying,
bring over the results, no matter what.
Show me all the messages.
So you're not saying, show me only attachments.
An inner join is just that.
So let's say, here, we could see 110 of these have attachments,
240 total.
There are 130 that don't have attachments.
Be careful with it.
Inner means only if it meets the requirements.
Left join is bring them all together anyway.
Show me everything.
So let's assume that there wasn't
a username for some reason.
If I did an inner join or just the word join,
it wouldn't bring over anything, except the ones with names.
So I would be missing all those contacts.
So left join is usually where I start.
In this next lab, you're going to see
the power of taking away that word left
and how it narrows down your search.