Effective PyCharm Transcripts
Chapter: Databases
Lecture: Modifying data with the console
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0:01
The final operation we want to work with here is to possibly change the schema,
0:06
what if we need to add a column, or add an index or something like that, we can go over here and right click and say modify column for existing ones
0:14
here we could change stuff about it like it could become unique or autoincrementing, or something like that
0:21
we could also go to the keys, go to the indexes and say we want to add an index on whatever, right go in here and add those things.
0:33
So we can edit it on the column by column or probably it makes more sense to modify the table like so, so we come over here and basically it was
0:44
as if we had double clicked one of these things it doesn't really matter that much but we could add say a column here
0:50
and this will be rating, and this is going to be an int, and the default will be two, and yeah, it's fine, we'll just go with that.
1:01
We can either execute this in the database, and notice this, this is really sweet, alter table,
1:06
this is the stuff I always forget when I'm working with relational databases, oh yeah, what's the DDL to change the type of a column
1:13
but it has data in it, so you have to like transform, like— what do I do. This is the kind of stuff you do right here, so here's the script
1:20
and I could hit just boom, execute it and it will modify the database or I could say just open this here in this editor
1:28
and I could make these changes and when I'm ready, I push this button and run it, and then I make the changes,
1:33
let's go over here comment that out and run this, alter table, one row is affected that sounds like something happened
1:42
and let's go resync, oh there is a rating, that's an integer, I don't like it anymore, we'll go over here and we can just remove it.
1:54
Alright, so we're going to begin a transaction drop a bunch of stuff, recreate it, that's pretty intense
1:58
but if we do that now our rating is gone again, so this modifying data— not the simplest thing to do in relational databases,
2:06
like I said at the start, I think this is one of the harder parts to evolve your database especially once it has data in it,
2:12
but, not too bad with the tools we have at hand here.