#100DaysOfCode in Python Transcripts
Chapter: Days 91-93: Database access with SQLAlchemy
Lecture: Your turn: Day 2
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On Day 2, you're going to focus on building out
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the database models and the database structure.
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So, recall from the presentation, that what you need to do
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is use some kind of base class that comes from
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SQLAlchemy, and have all of your models derive from that.
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So, here's the example we had for our move, in our game,
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and it derived from model base, we controlled the table,
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by putting table name in there.
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This is optional, but I like to do it.
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And then we just defined all the columns.
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Has integers, or has date times or strings,
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and then be sure to give it a primary key,
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and auto-increment if that's an integer, nice and easy.
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And then you're going to need to actually go and create
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the database, using your base model there.
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And create a session factory for use later.
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Alright, so if you run this code, already,
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you should actually have some kind of database file,
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and whatever you call it here, you'll have down here.
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And then, you can either look at it,
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if you're using Pycharm Pro, in Pycharm Pro,
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or you can use a DB Browser for SQLite.
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Either way, this is going to get your database structure
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all up and running.
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Final warning, or final note here:
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Beware, you cannot modify existing tables, so for example,
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this move, if I decided I also wanted some other value here,
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like the opponent's role, or you know, whatever,
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if I want to change this, at all, once I run this bit here,
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it's fixed, can't change it.
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SQLAlchemy will just ignore it, and it probably will crash
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when you try to work with it, who knows.
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So, if you want to do that, you need to use what's called
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migrations, or for this little example, the easiest way
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would be to just delete the database file, and start over
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and it will create it, new.
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But in production, migrations, or some kind of
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database script to do the change, is what's required.
