SQL Alchemy Other Notes
SQL Alchemy Other Notes
Schema
Database: This is the top-level container that holds the schemas. A database can contain multiple schemas.
Schema: Within a database, a schema is a collection of objects. It provides a way to namespace objects to avoid name collisions and to organize objects into logical groups.
Table: Within a schema, a table is one of the types of objects that stores data in rows and columns.
In table object, pass an argument of schema="X". In ORM definition, use __table_args__={'schema': 'X'}.
ORM Class to SQL Query
from sqlalchemy import create_engine, Column, Integer, String, MetaData
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy.schema import CreateTable
# Define the database connection
engine = create_engine('postgresql://user:password@localhost/mydatabase')
Base = declarative_base()
# Define your ORM class with the schema
class Employee(Base):
__tablename__ = 'employees'
__table_args__ = {'schema': 'hr'}
EmployeeID = Column(Integer, primary_key=True)
Name = Column(String)
Position = Column(String)
# Create a metadata instance
metadata = MetaData()
# Create the table object for Employee
employee_table = Employee.__table__
# Generate the SQL create table statement
create_table_sql = str(CreateTable(employee_table).compile(engine))
# Print the SQL statement
print(create_table_sql)
The query you created is supposed to be compatible with the engine you attached. But if you want to explicitly assign a dialect then, you the dialect argument.
from sqlalchemy_redshift.dialect import RedshiftDialect
create_table_sql = str(CreateTable(employee_table).compile(engine, dialect=RedshiftDialect()))
