Creating tables with SQLAlchemy
Previously, you used the Table object to reflect a table from an existing
database, but what if you wanted to create a new table? You'd still use the Table
object; however, you'd need to replace the autoload and autoload_with parameters with Column
objects.
The Column object takes a name, a SQLAlchemy type with an optional
format, and optional keyword arguments for different constraints.
When defining the table, recall how in the video Jason passed in 255 as the maximum length of a String by using Column('name', String(255)). Checking out the slides from the video may help.
After defining the table, you can create the table in the database by using the
.create_all() method on metadata and supplying the engine as the only parameter. Go for it!
Este ejercicio forma parte del curso
Introduction to Databases in Python
Instrucciones del ejercicio
- Import
Table,Column,String,Integer,Float,Booleanfromsqlalchemy. - Build a new table called
datawith columns'name'(String(255)),'count'(Integer()),'amount'(Float()), and'valid'(Boolean()) columns. The second argument ofTable()needs to bemetadata, which has already been initialized. - Create the table in the database by passing
enginetometadata.create_all().
Ejercicio interactivo práctico
Prueba este ejercicio y completa el código de muestra.
# Import Table, Column, String, Integer, Float, Boolean from sqlalchemy
from sqlalchemy import ____, ____, ____, ____, ____, ____
# Define a new table with a name, count, amount, and valid column: data
data = Table('data', ____,
Column(____, ____),
Column('count', Integer()),
Column(____, ____),
Column(____, ____)
)
# Use the metadata to create the table
metadata.create_all(____)
# Print table details
print(repr(data))