Fixing the SQL OperationalError When Using executemany for Insertions

Описание: Learn how to resolve the SQL OperationalError caused by incorrect placeholder syntax when inserting values in SQLite.
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This video is based on the question https://stackoverflow.com/q/68080024/ asked by the user 'Kathy' ( https://stackoverflow.com/u/16287812/ ) and on the answer https://stackoverflow.com/a/68085275/ provided by the user 'Kathy' ( https://stackoverflow.com/u/16287812/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the SQL OperationalError with executemany

When working with databases in Python, you might encounter various errors during data manipulation. One such error could be the OperationalError which arises while trying to execute multiple SQL commands. This is illustrated in the following example, where an attempt to insert records into a table using the executemany() method results in an error.

The Problem

In the code provided, the user attempts to insert multiple rows of data into a SQLite database table:

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The following SQL query is constructed:

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Upon executing the command:

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The user is met with the following error message:

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This indicates that there is a syntax error with the placeholders used in the SQL command.

The Solution

The solution to this error stems from understanding that different SQL dialects have unique syntax and placeholders for executing parameterized queries. In this case, the key point is:

SQLite uses ? as a placeholder instead of %s.

Step-by-step Solution

Change the Placeholders: Replace all occurrences of %s with ? in your SQL query string. The modified query should look like this:

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Execute the Query Again: With the corrected query, try running the executemany command once more:

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Check for Success: Once you run the code without encountering an OperationalError, you can confirm that the data has been successfully inserted into your SQLite database.

Why Does This Work?

Different database systems follow different conventions for identifying placeholders in SQL queries:

PostgreSQL/MySQL: Use %s as placeholders.

SQLite: Prefer ? for placeholder substitution.

Conclusion

If you ever find yourself facing the dreaded SQL OperationalError while executing database commands using Python's SQLite3 library, remember to check the placeholder syntax. In this case, switching from %s to ? resolved the issue.

We all make mistakes, and the learning process often involves navigating these small syntax differences. Keep exploring and don’t hesitate to look up documentation or ask for help when needed!