How to Execute Parameterized BigQuery SQL Inside a Python Function

Learn how to fix `BadRequest` errors when executing BigQuery SQL from Python by using standard SQL and string interpolation.
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Executing Parameterized BigQuery SQL Inside a Python Function

When working with BigQuery in Python, many developers encounter challenges, especially when trying to execute SQL queries that require parameters. A common issue is receiving a BadRequest error, particularly when running commands like CREATE OR REPLACE TABLE. If you’ve found yourself staring at a frustrating error message, you’re not alone. This guide will walk you through a solution that will help you successfully execute parameterized SQL in your Python functions, avoiding common pitfalls along the way.

The Problem

You may have written a Python function to execute a SQL command in BigQuery, but you are met with the following error:

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

This error typically occurs when using legacy SQL syntax with commands that are not compatible. The SQL command trying to run create or replace a table directly will not work correctly if the configuration is set to use legacy SQL.

Example Scenario

Here’s a simplified version of what your previous code might look like:

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

In this example, the configuration setting for legacy SQL is the obstacle that leads to the query failing.

The Solution

Step 1: Remove Legacy SQL Configuration

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

Step 2: Use String Interpolation

For better readability and maintainability of your code, switch from using the .format() method to Python’s f-strings for string interpolation. This will make the SQL query more straightforward. Here's how you can adjust the SQL string:

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

Final Adjusted Function

Revising the entire function looks like this:

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

Conclusion

By making these adjustments, you can eliminate the BadRequest error and successfully execute parameterized SQL queries in BigQuery from a Python function. Always remember to check if you are using standard SQL for operations like creating or replacing tables, and take advantage of Python's f-strings for clearer code.

Adopting these best practices will not only resolve the immediate issue but also lead to more robust and maintainable code in your future projects involving data pipelines with Python and BigQuery.

In your next project, have confidence in executing SQL directly from your Python code without running into frustrating errors!