first()
The first() method returns the first record from the query. It is similar to applying LIMIT 1 at the end of the SQL query. In the output, we can see that we were able to fetch a record from the table. However, if we try to iterate through the result we get an error that the object is not iterable, the reason being there is only one record present in the result.
Syntax: sqlalchemy.engine.Result.first()
Fetch the first row or None if no row is present. Closes the result set and discards remaining rows.
Python
from sqlalchemy.orm import sessionmaker import sqlalchemy as db from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() # DEFINE THE ENGINE (CONNECTION OBJECT) engine = db.create_engine( "mysql+pymysql://root:password@localhost/Geeks4Geeks" ) # CREATE THE TABLE MODEL TO USE IT FOR QUERYING class Profile(Base): __tablename__ = 'profile' email = db.Column(db.String( 50 ), primary_key = True ) name = db.Column(db.String( 100 )) contact = db.Column(db.Integer) class Students(Base): __tablename__ = 'students' first_name = db.Column(db.String( 50 ), primary_key = True ) last_name = db.Column(db.String( 50 ), primary_key = True ) course = db.Column(db.String( 50 ), primary_key = True ) score = db.Column(db. Float ) # CREATE A SESSION OBJECT TO INITIATE QUERY IN DATABASE Session = sessionmaker(bind = engine) session = Session() # SELECT * FROM profile LIMIT 1 result = session.query(Profile).first() print (result.email, "|" , result.name, "|" , result.contact) # VIEW THE ENTRIES IN THE RESULT for r in result: print (r.email, r.name, r.contact) |
Output:
SQLAlchemy ORM – Query
In this article, we will see how to query using SQLAlchemy ORM in Python.
To follow along with this article, we need to have sqlalchemy and anyone database installed in our system. We have used the MySQL database for this article’s understanding.
Created a Profile table and a Students table:
Here we are going to cover the following methods:
- add_columns()
- add_entity()
- count()
- delete()
- distinct()
- filter()
- get()
- first()
- group_by()
- join()
- one()