Resolving the Dynamic SQL Error with Firebird: Fixing Invalid Token Issues in Python

Learn how to troubleshoot the `SQL error code = -104 Token unknown` problem when using Python with Firebird, ensuring your database queries run smoothly and securely.
---
This video is based on the question stackoverflow.com/q/75245505/ asked by the user 'Kareem Etefy' ( stackoverflow.com/u/13065611/ ) and on the answer stackoverflow.com/a/75245940/ provided by the user 'Mark Rotteveel' ( stackoverflow.com/u/466862/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Dynamic SQL Error - SQL error code = -104 Token unknown happening on "select * from table". Python Firebird

Also, Content (except music) licensed under CC BY-SA meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Resolving the Dynamic SQL Error with Firebird: Fixing Invalid Token Issues in Python

When working with databases, encountering errors can be a common hurdle, especially when using dynamic SQL. One such error, SQL error code = -104 Token unknown, can prove to be frustrating. This post will dive into what causes this error specifically when working with the Firebird database in Python, and how to fix it effectively.

The Problem

In this case, the error arises when an attempt is made to execute a SQL query as follows:

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

The error message details:

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

Here, BLOB is the name of the table you're trying to query. The issue stems from the incorrect usage of single quotes around the table name, leading to the unexpected token error.

Understanding the Error

SQL Syntax Breakdown

In SQL, different types of identifiers need to be used correctly:

Single Quotes (') are used to denote string literals.

Double Quotes (") are used for quoting identifiers (like table or column names) when needed.

When you execute the SQL command:

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

Firebird interprets 'BLOB' as a string literal rather than a table name, resulting in the error because SQL expects either a valid identifier or double-quoted string for identifiers.

The Solution

To resolve this error, replace the single quotes around the table name with double quotes. Here’s how you can fix the problematic line in your code:

Updated Code Snippet

Replace:

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

with:

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

Why This Works

By using double quotes, you inform the Firebird engine that BLOB is indeed the identifier of a database table, which allows the query to run as intended.

Additional Security Considerations

While fixing the error is critical, it’s equally important to consider security implications. Using string interpolation can make your code susceptible to SQL injection attacks. To safeguard against this, especially in cases where you receive user inputs, consider using parameterized queries.

Example of Parameterized Queries

Instead of:

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

Use:

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

This way, you decouple your data from the SQL command, enhancing security.

Conclusion

In summary, the Dynamic SQL Error you encountered while working with Firebird can be directly addressed by replacing single quotes with double quotes around table names. Additionally, safeguarding your application from potential SQL injection attacks by leveraging parameterized queries is advisable. With these changes, you can streamline your data queries and reduce the chance of errors significantly.

Feel free to reach out if you encounter any further issues, or have additional questions regarding Python and Firebird!