Export Microsoft SQL Data To CSV Using Python

Introduction

In this article, you will learn how to create REST API to read Microsoft SQL table and export the result to CSV file using Python. I have created a simple Microsoft SQL table for this demo named as Employees which contains the following columns and rows.

Topics Covered

This article demonstrates how to build the following:

• Create the project folder
• Install the required packages
• Implement the REST API
• Test the API

Prerequisites

1. Windows machine and Visual Studio code are used for this article. Complete all the prerequisites mentioned in this article.
2. Install the Microsoft ODBC Driver for SQL Server on Windows.

Tools

1. Visual Studio Code

Task 1: Create the project folder

In this task, you will see how to create the project folder.

Step 1

Open Windows Command Prompt and run the following commands to create the new folder for this project.

mkdir ExportDataCSV
cd .\ExportDataCSV

Task 2: Install the required packages

In this task, you will see how to install the required packages for this project.

Step 1

Open ExportDataCSV folder in Visual Studio Code. Click Terminal -> New Terminal.

Step 2

Run the following command to install the packages required for this project.

pip install flask
pip install flask-restful
pip install pyodbc
pip install pandas

• flask is a simple framework for building complex web applications.
• flask-restful is an extension for Flask that adds support for quickly building REST APIs
• pyodbc is an open source Python module that makes accessing ODBC databases simple.
• pandas provides fast, flexible, and expressive data structures designed to make working with “relational” or “labeled” data both easy and intuitive.

Task 3: Implement the REST API

In this task, you will see how to implement the REST API to read the Microsoft SQL table and export the results to CSV file.

Step 1

In Visual Studio Code, create a new file app.py under ExportDataCSV folder. Note: Update the connection string value.

Step 2

Copy and paste the below code.

from flask import Flask
from flask_restful import Resource, Api
import pyodbc 
from datetime import date
import pandas as pd

# Input Parameters
getdatacmd='SELECT id AS EmployeeId, name AS Name, designation AS Designation, location AS Location FROM Employees'
connstring='DRIVER={ODBC Driver 18 for SQL Server};SERVER=LHR-********\SQLEXPRESS;DATABASE=demo;ENCRYPT=no;Trusted_Connection=yes;'
today=date.today().strftime('%d.%m.%Y')
filename='exported_data'+today+'.csv'

# Create the flask app
app = Flask(__name__)
# Create an API object
api = Api(app)
 
# Class for ExportToCSV
class ExportToCSV(Resource):
    # GET Request
	def get(self):
		cnxn = pyodbc.connect(connstring)
		sql_query = pd.read_sql_query( getdatacmd,cnxn)
		df = pd.DataFrame(sql_query)
		df.to_csv (filename, index = False)
		return filename + ' is exported successfully'
	
# Add the defined resources along with their corresponding urls
api.add_resource(ExportToCSV, '/')

# Driver function
if __name__ == '__main__':

	app.run(debug = True)

Task 3: Test the API

In this task, you will see how to test the API which creates the CSV file with data read from Microsoft SQL table.

Step 1

In Visual Studio Code, run the following command in the Terminal.

python .\app.py 

Step 2

Open the browser and access the below URL. CSV file gets created in ExportDataCSV folder as shown below.

http://127.0.0.1:5000/

References

1. Flask-RESTful documentation
2. Python SQL Driver - pyodbc
3. pandas.DataFrame.to_csv

Summary

This article describes how to read Microsoft SQL table and export the result to CSV file using Python.