How to use Python cursor’s fetchall, fetchmany(), fetchone() to read records from SQL

This article demonstrates the use of Python’s cursor class methods fetchall, fetchmany(), fetchone() to retrieve rows from a database table. This article applies to all the relational databases, for example, MySQL, PostgreSQL.

We generally use the following Python module to work with Database.

• MySQL — — — — MySQL Connector Pytho
• PostgreSQL — — — — Psycopg2
• SQLite — — — — sqlite3

Above all, interfaces or modules are adhere to Python Database API Specification v2.0 (PEP 249). In this article, I will show how to use fetchall, fetchmany(), fetchone() to retrieve data from MySQL, PostgreSQL, SQLite database.

Before proceeding further first understand what is the use of fetchall(), fetchmany(), fetchone().

cursor.fetchall() returns all the rows of a query result. It returns all the rows as a list of tuples. An empty list is returned if there is no record to fetch.

cursor.fetchmany(size) returns the number of rows specified by size argument. When called repeatedly this method fetches the next set of rows of a query result and returns a list of tuples. If no more rows are available, it returns an empty list.