Solving the executemany() Issue with MariaDB in Python

Learn how to efficiently use `executemany()` for inserting multiple rows into MariaDB, even when dependent on SELECT statements.
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Introduction

In the world of database management, especially when working with MariaDB and Python, performance is key. Many developers seek to speed up their operations by inserting multiple rows simultaneously using the executemany() function. However, a common stumbling block arises when the values to be inserted depend on a SELECT query — leading to complications since SELECT statements do not work within executemany(). In this guide, we’ll explore this issue and offer a viable solution for handling data insertion effectively.

Understanding the Problem

You are working on a project where you need to insert multiple rows into a MariaDB table. Each row's data depends on values retrieved from other tables via SELECT queries. Unfortunately, attempting to execute a query that combines an INSERT statement with SELECT within executemany() has proven unsuccessful. Instead, you find that it repeatedly returns the same value for the column pulled from the SELECT query, corresponding to the first set of input data processed.

Your Current Approach

Your current SQL query structure looks like this:

[[See Video to Reveal this Text or Code Snippet]]

You intended to gather values from table2 and table3 to be inserted into table1. But since executemany() doesn’t allow a SELECT statement directly, you are left with repeated data for your first tuple of input.

Solution: Retrieving Data Before Insertion

To overcome the limitation of executemany() with SELECT statements, consider a two-step solution: first, retrieve the necessary data through separate queries in Python, and then use executemany() to handle the data insertion. Here's a detailed breakdown of how to implement this solution:

Step 1: Fetch Required Data

Before inserting data into your target table, you'll need to gather the relevant values from table2 and table3. This can be achieved with the following steps:

Connect to MariaDB: Ensure you have a connection to your database.

Execute SELECT Queries: Perform two SELECT queries to gather the necessary data based on your input criteria.

Organize Retrieved Data: Store the results in a suitable data structure for easy access during insertion.

Example Code:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Use executemany() for Insertion

Once you have your results ready in the appropriate format, you can then use the executemany() function for efficient insertion into table1.

Example Code:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

In conclusion, while executemany() presents a convenient way to insert multiple rows, encountering SELECT statements within it requires rethinking your approach. By fetching the necessary data first and then inserting it with executemany(), you can efficiently manage large datasets in MariaDB with the performance advantages you initially sought. This method mitigates the constraints caused by the combination of INSERT and SELECT operations, allowing your application to function as intended.

Now you can implement this solution in your project and enjoy the benefits of faster data operations.