Retrieving Count of Rows Between Two Dates Using SQLite3 Query in Python

This article explains how to use a SQLite3 query in Python to retrieve the count of rows between two dates using the pandas library.

Introduction

SQLite is a lightweight disk-based database that can be used in various applications. It provides an efficient way to store and manipulate data. In this article, we will explore how to use SQLite3 with Python to achieve a common task: retrieving the count of rows between two dates.

We will start by understanding the basics of SQLite and its query language, then move on to using it with Python. We will also discuss how to optimize the query for better performance.

Setting Up the Environment

Before we dive into the code, let’s set up our environment.

# Install necessary libraries
pip install sqlite3 pandas

Creating a SQLite Database Connection

To connect to the database, we need to create a connection object. This can be done using the sqlite3.connect() function from the Python standard library.

import sqlite3 as lite

# Function to create DB connection and raise error
def create_connection(db_file):
    """ create a database connection to the SQLite database
        specified by db_file
    :param db_file: database file
    :return: Connection object or None
    """
    conn = None
    try:
        conn = lite.connect(db_file)
        return conn
    except lite.Error as e:
        print(e)

    return conn

# Create connection to DB and create df
conn = create_connection('test.db')

Reading Data from the Database Using Pandas

Once we have connected to the database, we can use the pandas library to read data from it.

import pandas as pd

df = pd.read_sql("SELECT * FROM data;", conn)

Creating a Cursor Object

To execute SQL queries on the database, we need to create a cursor object. This can be done using the conn.cursor() method.

cur = conn.cursor()

Retrieving Count of Rows Between Two Dates

Now that we have connected to the database and created a cursor object, let’s move on to retrieving the count of rows between two dates.

The problem with your code is that you have set the starting and ending values of the operator BETWEEN reversed. It should be:

BETWEEN datetime('{}', '-15 day') AND datetime('{}')

However, I would also suggest using ? placeholders to pass the parameters. Also, there is no need to use the datetime() or date() functions to get a date if it is already in the format YYYY-MM-DD.

Use this:

sql = "SELECT COUNT(*) FROM bt WHERE id = ? AND btdate BETWEEN date(?, '-15 day') AND ?;"
cur.execute(sql, (row['id'], row['date'], row['date']))

This will execute the SQL query and return a list containing the count of rows that meet the condition.

Optimizing the Query

To optimize the query for better performance, we can use an index on the btdate column. This can be done by running the following SQL command:

CREATE INDEX idx_btdate ON bt (btdate);

This will create an index on the btdate column, which can speed up the execution of the query.

Conclusion

In this article, we have discussed how to use a SQLite3 query in Python to retrieve the count of rows between two dates. We covered topics such as creating a database connection, reading data from the database using pandas, and optimizing the query for better performance.

Last modified on 2025-03-22