Python Learning Note eight: ORM Framework SQLAlchemy

One: SQLAlchemy use

1: Creation of entity classes

The entity classes in ORM are different from the generic Python class, where __tablename__= "" is used to indicate that the class corresponds to a table in the database, and then defines a series of member properties that use Column (data type) To map to a specific column in the table.

First, create the database engine and get a base class from a static method: Declarative_base () creates a Basemodel class that can be automatically associated with a table subclass.

Then, inherit the base class and define the entity class:

Entity classes with foreign keys are created:

Finally, run the method that comes with the base class, pass the database engine in, create the database table: BaseModel.metadata.create_all will find all the subclasses of Basemodel and build them in the database

2: Create a record

Creates a class instance that corresponds to a database record.

3: Create a database session

4: Manipulating the database using an object-oriented approach

Increase:

Add a record:

Add multiple records:

Check:

Conditional query:

Full Table query:

Sort query:

Filter query (In/not in):

Statistics Query record number:

Logical query: and/or followed by left and right operands.

Join query:

Other things to do: Refer to this blog post:

http://blog.csdn.net/fengzhongzhishenfu/article/details/38978863

5: Commit the transaction for the persistence operation to take effect

Python Learning Note eight: ORM Framework SQLAlchemy