SQLAlchemy Core

SQLAlchemy ORM

In this example, we have used the SQLAlchemy Core. The already created students table is referred which contains 4 columns, namely, first_name, last_name, course, and score. But we will be only selecting a specific column. In the example, we have referred to the first_name and last_name columns. Other columns can also be provided in the entities list.

By using the select() method:

Python

import sqlalchemy as db
 
# Define the Engine (Connection Object)
engine = db.create_engine("mysql+pymysql://\
root:password@localhost/Geeks4Geeks")
 
# Create the Metadata Object
meta_data = db.MetaData()
meta_data.reflect(bind=engine)
 
#don't follow the following syntax for creating the meta_data
#meta_data=MetaData(bind=engine)
#Here MetaData class doesn't have any argument bind,so we get arror.
 
 
# Get the `students` table from the Metadata object
STUDENTS = meta_data.tables['students']
 
# SQLAlchemy Query to SELECT specific column
query = db.select(
    STUDENTS.c.first_name,
    STUDENTS.c.last_name
)
#don't use [STUDENT.c.first_name,....] give ArgumentError
#[STUDENT.c.first_name,....] the syntax in older versions only
 
# Fetch all the records
result = engine.execute(query).fetchall()
 
# View the records
for record in result:
    print("\n", record[0], record[1])

Output:

Output – SQLAlchemy Core

Querying and selecting specific column in SQLAlchemy

In this article, we will see how to query and select specific columns using SQLAlchemy in and

For our examples, we have already created a Students table which we will be using:

Selecting specific column in SQLAlchemy:

Syntax: sqlalchemy.select(*entities)

Where: Entities to SELECT from. This is typically a series of ColumnElement for Core usage and ORM-mapped classes for ORM usage.

Tags:

#python #Python SQLAlchemy-Core #Python SQLAlchemy-ORM #Python-SQLAlchemy #Python #python #python