Sqlalchemy Online Tutorials

SQLAlchemy is an open-source Python library that provides an SQL toolkit (called "SQLAlchemy Core") and an Object Relational Mapper (ORM) for database interactions. It allows developers to work with databases using Python objects, enabling efficient and flexible database access.

Original author(s)Michael Bayer
Initial releaseFebruary 14, 2006; 19 years ago (2006-02-14)
Stable release
2.0.40 Edit this on Wikidata / 27 March 2025; 16 days ago (27 March 2025)
Repository
  • github.com/sqlalchemy/sqlalchemy Edit this at Wikidata
Written inPython
Operating systemCross-platform
TypeObject-relational mapping
LicenseMIT License
Websitewww.sqlalchemy.org Edit this on Wikidata
Mike Bayer talking about SQLAlchemy at PyCon 2012

Description

edit

SQLAlchemy offers tools for database schema generation, querying, and object-relational mapping. Key features include:

  • A comprehensive embedded domain-specific language for SQL in Python called "SQLAlchemy Core" that provides means to construct and execute SQL queries.
  • A powerful ORM that allows the mapping of Python classes to database tables.
  • Support for database schema migrations.
  • Compatibility with multiple database backends.
  • Tools for database connection pooling and transaction management.

History

edit

SQLAlchemy was first released in February 2006. It has evolved to include a wide range of features for database interaction and has gained popularity among Python developers. Notable versions include:

  • Version 0.1 (2006):[5] Initial release.
  • Version 1.0 (2015):[6] Major enhancements in ORM and SQL expression language.
  • Version 1.4 (2021):[7] Introduction of a new ORM API.

Example

edit

The following example represents an n-to-1 relationship between movies and their directors. It is shown how user-defined Python classes create corresponding database tables, how instances with relationships are created from either side of the relationship, and finally how the data can be queried — illustrating automatically generated SQL queries for both lazy and eager loading.

Schema definition

edit

Creating two Python classes and corresponding database tables in the DBMS: 

from sqlalchemy import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relation, sessionmaker

Base = declarative_base()

class Movie(Base):
    __tablename__ = "movies"

    id = Column(Integer, primary_key=True)
    title = Column(String(255), nullable=False)
    year = Column(Integer)
    directed_by = Column(Integer, ForeignKey("directors.id"))

    director = relation("Director", backref="movies", lazy=False)

    def __init__(self, title=None, year=None):
        self.title = title
        self.year = year

    def __repr__(self):
        return f"Movie({self.title}, {self.year}, {self.director})"

class Director(Base):
    __tablename__ = "directors"

    id = Column(Integer, primary_key=True)
    name = Column(String(50), nullable=False, unique=True)

    def __init__(self, name=None):
        self.name = name

    def __repr__(self):
        return f"Director({self.name})"

engine = create_engine("dbms://user:pwd@host/dbname")
Base.metadata.create_all(engine)

Data insertion

edit

One can insert a director-movie relationship via either entity: 

Session = sessionmaker(bind=engine)
session = Session()

m1 = Movie("Robocop", 1987)
m1.director = Director(<
		 	 
Sqlalchemy Tutorials:  	
	SQLAlchemy is a Python SQL toolkit and Object Relational Mapper that gives application developers the full power and flexibility of SQL

		 		 




			 		

				





 

 		
 

 




Latest online Sqlalchemy Tutorials  with example so this page for both freshers and  experienced candidate who want to get job in Sqlalchemy company


	
   

 

  
   
Latest online Sqlalchemy Tutorials for both freshers and experienced


   		 advertisements

	




View Tutorials on Sqlalchemy  View all questions







	
	 

 
 
 
 

Ask your interview questions on Sqlalchemy







Write Your comment or Questions if you want the answers on Sqlalchemy from Sqlalchemy Experts 





  Name* :

  
Email Id* :

    
Mob no* :


Question 
 Or 
 Comment* : 


  




Disclimer: PCDS.CO.IN not responsible for any content, information, data or any feature of website. If you are using this website then its your own responsibility to understand the content of the website

--------- Tutorials ---