Adventures in Machine Learning

Python and SQL Server: Inserting and Verifying Data Easily

Inserting Values into SQL Server Table Using Python

Are you looking for a comprehensive guide on how to insert values into a SQL Server table using Python? Look no further! This article will walk you through the steps needed to connect your Python application to SQL Server and start inserting values.

Step 1: Installing Pyodbc Package

The first step in inserting values into a SQL Server table using Python is to install the Pyodbc package. Pyodbc is a Python module that allows you to connect to databases using the Open Database Connectivity (ODBC) API.

The installation process for Pyodbc is straightforward. Open your command prompt, navigate to the directory where you want to install Pyodbc, and enter the following command:

pip install pyodbc

Step 2: Connecting Python to SQL Server

Before you can insert values into a SQL Server table using Python, you need to connect to the SQL Server instance. To do this, you need to retrieve the server name, database name, and table name.

To connect to SQL Server, you will first need to import the Pyodbc module and use the ‘connect’ function to create a connection string. The format of the connection string will depend on the server name, database name, and authentication method.

Here’s an example code snippet that connects Python to SQL Server using Windows Authentication, where Server_Name is the name of the server, Database_Name is the name of the database, and Table_Name is the name of the table you plan to insert values into:

import pyodbc 
# Retrieve server, database, and table names
Server_Name = 'your_server_name'
Database_Name = 'your_database_name'
Table_Name = 'your_table_name'
# Connect to SQL Server instance using Windows Authentication 
con = pyodbc.connect('Trusted_Connection=yes', driver = '{SQL Server}',server = Server_Name, database = Database_Name)

Note that if you use SQL Server Authentication, you will need to provide a user name and password in addition to the server, database, and table names.

Step 3: Inserting Values into SQL Server Table Using Python

Now that you’ve connected Python to SQL Server, you can start inserting values into the corresponding table. To insert values using Python, you will need to use SQL INSERT statements.

Here’s an example code snippet that inserts values into a Product table:

import pyodbc 
# Retrieve server, database, and table names
Server_Name = 'your_server_name'
Database_Name = 'your_database_name'
Table_Name = 'Product'
# Connect to SQL Server instance using Windows Authentication 
con = pyodbc.connect('Trusted_Connection=yes', driver = '{SQL Server}',server = Server_Name, database = Database_Name)
# Create a cursor object to execute SQL statements
cursor = con.cursor()
# Define the SQL INSERT statement
insert_query = '''INSERT INTO {} ([Product_Name], [Product_Price], [Product_Category])
                  VALUES (?, ?, ?)'''.format(Table_Name)
# Define the values to be inserted into the Product table
Product_Name = 'T-Shirt'
Product_Price = 25.99
Product_Category = 'Clothing'
# Executing the SQL INSERT statement using placeholders
cursor.execute(insert_query, (Product_Name, Product_Price, Product_Category))
# Commit the transaction to persist the changes
con.commit()
# Print the number of rows inserted
print(cursor.rowcount, "row(s) were inserted.")

In this example, Python inserts a new row into the ‘Product’ table using placeholders for the values. The placeholders prevent SQL injection attacks and make it easy to pass in variables when executing the query.

Step 4: Verifying the Results

After inserting values into a SQL Server table using Python, you may want to verify that the changes have been made. You can do this by executing a SELECT statement and retrieving the data from the SQL Server table.

Here’s an example code snippet that retrieves all rows from a ‘Product’ table:

import pyodbc 
# Retrieve server, database, and table names
Server_Name = 'your_server_name'
Database_Name = 'your_database_name'
Table_Name = 'Product'
# Connect to SQL Server instance using Windows Authentication 
con = pyodbc.connect('Trusted_Connection=yes', driver = '{SQL Server}',server = Server_Name, database = Database_Name)
# Create a cursor object to execute SQL statements
cursor = con.cursor()
# Define a SELECT statement to retrieve all rows from the Product table
select_query = '''SELECT * FROM {}'''.format(Table_Name)
# Executes the SELECT statement and retrieves all rows
cursor.execute(select_query)
rows = cursor.fetchall()
# Print the data from the Product table
for row in rows:
    print(row)

In this example, Python retrieves all the rows from the ‘Product’ table and prints each row to the console. This allows you to verify that the changes made by the previous INSERT statement are reflected in the SQL Server table.

Example Database Information

For the purpose of this article, we’ll use a sample ‘Product’ table. The ‘Product’ table has three columns – Product_Name, Product_Price, and Product_Category – and contains information about various products.

Here’s an example of what the ‘Product’ table might look like:

Product_Name    Product_Price    Product_Category
T-Shirt            25.99              Clothing
Coffee Mug        9.99               Drinkware

Connecting Python to SQL Server

Python is a powerful programming language that can be used in a variety of data-related tasks. One of its most common use cases is to connect to a SQL Server database to retrieve data or insert new values.

The process of connecting Python to SQL Server involves several steps, which we will go over in detail below.

Step 1: Importing Pyodbc Package

The first step in connecting Python to SQL Server is to import the Pyodbc package.

This package is responsible for connecting to the database and executing SQL queries. To import Pyodbc, simply navigate to your Python file and add the following line at the top of the file:

import pyodbc

Step 2: Establishing Connection

Once you have imported the Pyodbc package, the next step is to create a connection to your SQL Server database. To do this, you will need to specify the server name, database name, and login details, including the username and password.

Here’s an example code snippet that establishes a connection to a SQL Server database using Windows Authentication:

import pyodbc
server_name = ''
database_name = ''
# Create a connection object
connection = pyodbc.connect('DRIVER={SQL Server};SERVER=' + server_name + ';DATABASE=' + database_name + ';Trusted_Connection=yes')

In this example, the server name and database name variables are initialized to the actual server and database names. The connect() function uses a connection string to connect to the specified SQL Server instance.

Step 3: Retrieving Data

Now that you have established a connection to your SQL Server database, you can use Python to retrieve data from it. To do this, you will need to create a cursor object, which allows you to execute SQL statements and retrieve the results.

Here’s an example Python code snippet that retrieves data from a SQL Server database:

import pyodbc
server_name = ''
database_name = ''
# Connect to SQL Server instance using Windows Authentication
connection = pyodbc.connect('DRIVER={SQL Server};SERVER=' + server_name + ';DATABASE=' + database_name + ';Trusted_Connection=yes')
# Create a cursor object
cursor = connection.cursor()
# Select Data from a table
sql_query = 'SELECT * FROM '
cursor.execute(sql_query)
# Fetch all the rows from the cursor  
result_set = cursor.fetchall()

In this code snippet, the cursor object is created by calling the connection object’s cursor() method. Next, a SQL query is defined, which retrieves data from a specific table.

The execute() method is then called on the cursor object, which executes the query and fetches all the rows using the fetchall() method.

Inserting Values into SQL Server Table

Inserting values into a SQL Server table using Python is a common use case for data-related tasks. Python makes this process very simple by using SQL INSERT statements.

The process of inserting values into a table using Python involves three main steps.

Step 1: Establishing Connection

The first step in inserting values into a SQL Server table using Python is to establish a connection to the database.

This step is the same as described in the previous section, involving defining the server name, database name, and login details.

import pyodbc
server_name = ''
database_name = ''
# Create a connection object
connection = pyodbc.connect('DRIVER={SQL Server};SERVER=' + server_name + ';DATABASE=' + database_name + ';Trusted_Connection=yes')

Step 2: Writing Insert Query

The next step is to write the SQL INSERT statement. The INSERT statement takes the values that should be inserted into the table.

To include variable data in the SQL query, placeholders are used to represent the values that will be inserted.

Here’s an example Python code snippet that demonstrates how to insert data into a SQL Server table:

import pyodbc
server_name = ''
database_name = ''
# Create a connection object
connection = pyodbc.connect('DRIVER={SQL Server};SERVER=' + server_name + ';DATABASE=' + database_name + ';Trusted_Connection=yes')
# Create a cursor object
cursor = connection.cursor()
# Insert values into table
sql_query = "INSERT INTO  (col1, col2) VALUES (?, ?)"
values = ('value1', 'value2')
cursor.execute(sql_query, values)

Step 3: Committing Changes

After the INSERT statement has been executed, the changes will not be committed to the database until the transaction is committed. To commit the changes and confirm that the inserted values are saved in the table, the connection object’s commit() method can be called.

Here’s the final example Python code snippet that covers all three steps of inserting data into a SQL Server table:

import pyodbc
server_name = ''
database_name = ''
# Create a connection object
connection = pyodbc.connect('DRIVER={SQL Server};SERVER=' + server_name + ';DATABASE=' + database_name + ';Trusted_Connection=yes')
# Create a cursor object
cursor = connection.cursor()
# Insert values into table
sql_query = "INSERT INTO  (col1, col2) VALUES (?, ?)"
values = ('value1', 'value2')
cursor.execute(sql_query, values)
# Commit the transaction
connection.commit()

In this code snippet, the connection object is used to create a cursor object, which is used to insert new records into a SQL Server table. Once the INSERT statement has been executed, the changes are committed to the database by calling the connection object’s commit() method.

Verifying Results

Once you have inserted data into a SQL Server table using Python, it is important to verify that the values have been successfully added to the table. One way to do this is by executing a SELECT statement that retrieves the inserted data.

Step 1: Establishing Connection

Before you can verify the results, you need to establish a connection to the SQL Server database using Python, as shown in the previous section.

import pyodbc
server_name = ''
database_name = ''
# Create a connection object
connection = pyodbc.connect('DRIVER={SQL Server};SERVER=' + server_name + ';DATABASE=' + database_name + ';Trusted_Connection=yes')

Step 2: Executing a Select Query

To retrieve the inserted data from the SQL Server table using Python, you can execute a SELECT statement. Here’s an example Python code snippet that demonstrates how to retrieve data using a SELECT statement:

import pyodbc
server_name = ''
database_name = ''
# Create a connection object
connection = pyodbc.connect('DRIVER={SQL Server};SERVER=' + server_name + ';DATABASE=' + database_name + ';Trusted_Connection=yes')
# Create a cursor object
cursor = connection.cursor()
# Execute a SELECT statement
select_query = "SELECT * FROM "
cursor.execute(select_query)
# Fetch all the rows from the cursor  
result_set = cursor.fetchall()
# Print the result set
for row in result_set:
    print(row)

In this code snippet, the SELECT statement is executed using the cursor object’s execute() method. After the SELECT statement has been executed, the fetchall() method is called on the cursor object to retrieve the results.

The results are stored in the result_set variable, which is then printed to the console.

Step 3: Verifying the Results

Once you have printed the result set to the console, you can verify that the inserted data is present in the SQL Server table.

Here’s an example output of the result_set variable:

('value1', 'value2', 'value3')
('value4', 'value5', 'value6')

This output confirms that two rows with three columns each were inserted into the SQL Server table successfully.

In addition to verifying the data has been inserted correctly, you can also use WHERE clauses and other filtering options to perform more in-depth queries on the data to confirm that it meets your accuracy requirements.

Conclusion

In this article, we covered the steps required to establish a connection to a SQL Server database using Python, execute a SELECT statement, and verify the results. By following these steps, you can ensure that the data you are working with is accurate and has been successfully inserted into the SQL Server table.

With the addition of WHERE clauses and other filtering options, you can create more complex queries to perform in-depth verification of your data.

In this article, we discussed how to connect Python to SQL Server and insert data into a table using Python.

We also covered the importance of verifying the results by executing a SELECT statement. By following the outlined steps and creating a connection to the database, executing a SQL statement, and verifying the results, Python developers can interact with SQL Server more effectively and carry out their desired data-related tasks.

With our comprehensive guide, we hope to have equipped Python developers with the tools they need to work with SQL Server effectively and efficiently.

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