SQL Alchemy Tutorial

SQL Alchemy is a powerful and popular Python library that provides an Object-Relational Mapping (ORM) tool for working with relational databases. It serves as a bridge between Python and various database management systems, allowing developers to interact with databases using Python code.

In this blog, we will discuss about the following topics:

• SQL Alchemy
• ORM Mapper
• Relation between Python and SQL Alchemy
• SQL Alchemy Installation
• CRUD Operation

The Python SQL toolkit known as SQLAlchemy enables programmers to manage and access SQL databases using the Pythonic domain language. For comparable searches of  SQL Alchemy you can chain Python objects or write your query as a string. Developers have more freedom when working with objects, which also enables them to create high-performance SQL-based systems.

SQL alchemy features:

• An effective ORM that is built on the identity map, unit of work, and data mapper principles at its heart.These principles enable object transparency through a declarative configuration framework. Domain models can be built and modified naturally, and updates are automatically synchronized with the current transaction.
• A relationally based query system that openly exposes the joins, subqueries, and correlation in terms of the object model capabilities of SQL. Writing queries using the relational composition ORM techniques you use while writing SQL 
• An extensive and adaptable enthusiastic load method for related collections and objects Collections can be loaded individually, all at once via joins, or by querying each collection individually throughout the entire result set. Collections are cached inside a session.

ORM Mapper:

The object-relational mapping (ORM) technique is implemented by a software component known as an ORM mapper. A relational database’s data can be mapped to objects in an object-oriented programming language using a technique called ORM. The ORM mapper creates an abstraction layer between the database and the objects, allowing the manipulation of the objects without requiring knowledge of the underlying database structure.

An object-to-database table mapping is how the ORM mapper normally functions. The mapping specifies how the characteristics of the object relate to the columns in the database table. The translation between the objects and the database is subsequently performed by the ORM mapper using this mapping. The ORM mapper will insert an object’s data into the database table when the object is created. The ORM mapper will update the relevant data in the database table whenever an object is updated. The ORM mapper will remove the associated data from the database table when an object is destroyed.

Relation between Python and SQL Alchemy

SQLAlchemy provides a number of features that make it easy to work with databases in Python. These features include:

• • Object-Relational Mapping (ORM): The ORM allows you to access and manipulate data in a database using Python objects and classes. This makes it much easier to work with databases in Python than using raw SQL.
  • Declarative Programming: SQLAlchemy supports declarative programming, which makes it easy to define the structure of your database tables and the relationships between them.
  • Extensible: SQLAlchemy is a very extensible library. You can customize it to meet your specific needs.

Overall, SQLAlchemy is a powerful and versatile library that can be used to interact with a variety of relational and NoSQL databases in Python.

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SQL Alchemy Installation

You can also install SQLAlchemy from the source code. To do this, download the source code from the SQLAlchemy website and follow the instructions in the README file. Once you have installed SQLAlchemy, you can start using it to connect to a database and perform queries. For more information, please see the SQLAlchemy documentation.

Now, let me explain you this with demo how to implement SQL Alchemy with Python. You need to follow few steps to start using it.

• Adjusting DB Browser for viewing. To do the following download DB browser by pressing Ctrl+Alt+S on

pycharm IDE 🡪 Search “DB Navigator”

• To View the database on PyCharm IDE undertake the following tasks:

• Click on SQLite

• Copy the absolute path of the database and post it on the file path for database and test the connection

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CRUD OPERATIONS

CRUD, which stands for Create, Read, Update, and Delete, are the four basic operations that are performed on data stored in a database. These operations form the foundation of any database-driven applications. SQLAlchemy, you can perform CRUD operations using the following methods:

• Create: The create() method is used to create a new row in a table.

To perform CRUD operations in SQLAlchemy, we first need to define the schema for our data. A schema is a blueprint that describes the structure of the data that will be stored in the database. In our stock ticker tracking application, we will need a table to store information about the stocks that we are tracking.

To define the schema for our table, we will use SQLAlchemy’ s declarative base class, which provides a base class for creating the schema of our tables. First, we need to import the class and create an instance of it:

• Read: The read() method is used to retrieve rows from a table.

To perform read operations using SQLAlchemy, you can use query methods to retrieve    data from the database. Here’s an example of a read operation using SQLAlchemy in Python:

• Update: The update() method is used to update the values of existing rows in a table.

To perform an update operation using SQL Alchemy, you can retrieve a record from the database, modify its attributes, and then commit the changes. Here’s an example of an update operation using SQL Alchemy in Python:

• Delete: The delete() method is used to delete rows from a table.

To perform a delete operation using SQL Alchemy, you can retrieve a record from the database and then remove it from the session. Here’s an example of a delete operation using SQL Alchemy in Python:

In conclusion, SQL Alchemy is a powerful Python library that provides a convenient and intuitive way to interact with relational databases. It allows you to perform CRUD operations (Create, Read, Update, Delete) efficiently and effectively. SQL Alchemy offers a flexible and comprehensive approach to database operations in Python, supporting various database management systems and providing a high-level API that simplifies the process of working with databases. For more such information, you can visit our website for interesting and informative blogs. https://www.edureka.co/