Скачать или смотреть Resolving the QSqlDatabase not connecting Issue in Ubuntu 20.04

Learn how to troubleshoot the `QSqlDatabase not connecting` issue on Ubuntu 20.04 when trying to connect to a SQLite database using Qt.
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This video is based on the question https://stackoverflow.com/q/76104961/ asked by the user 'Mustafa Aslan' ( https://stackoverflow.com/u/16571955/ ) and on the answer https://stackoverflow.com/a/76105608/ provided by the user 'Mike' ( https://stackoverflow.com/u/9619730/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting QSqlDatabase Connection Issues in Ubuntu 20.04

If you’ve been working with Qt and SQLite, you might have encountered a frustrating situation where your database doesn’t seem to connect, despite all the coding efforts you’ve put in. This is particularly common on Ubuntu systems, and that’s what we’ll explore today. Let's dive into understanding the common problems and how to resolve them efficiently.

The Problem: QSqlDatabase Not Connecting

In a recent experience shared by a user coding on Ubuntu 20.04, the challenge arose when attempting to connect to a SQLite database named database.db. Although the connection appeared to open, and the queries executed without any noticeable errors, the database file remained empty. This led to confusion, leaving many wondering if they were inadvertently creating a temporary database instead of writing to the specified file.

Key Observations

The code seemed to run just fine, but changes didn’t reflect in the database.db file.

Users noticed that even though successful execution messages appeared, the database did not contain the expected data or table.

The Solution: Correctly Setting Up Your Database Connection

To ensure a successful connection and data storage within your SQLite database, a small adjustment in your code is necessary. Let’s break it down into clear steps.

Step 1: Use the Correct Database Initialization

While initially, the user employed the following code:

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

This approach erroneously sets the username when you should actually be specifying the database name. Here’s the revision you need to implement:

Updated Code Snippet

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

Step 2: Key Changes Explained

Setting Database Name: The crucial change here is to call con.setDatabaseName(dbName); instead of con.setUserName(). This correctly links your SQLite database file with your connection.

Host Name: It's typically unnecessary to set a host name for SQLite databases. Therefore, you can omit con.setHostName(dbName); for SQLite connections.

Proper Query Execution: Following the connection, ensure you properly execute your queries to create tables or insert data.

Final Advice

After implementing the changes mentioned above, try compiling and running your program again. With these adjustments, your SQLite database should now accurately reflect the changes and data you input, as verified via tools like SQLite Browser.

Conclusion

Dealing with database connections can be tricky, especially when settings seem correct but results don’t reflect your commands. By understanding the setup process and ensuring you are using the correct functions, connecting to QSqlDatabase on Ubuntu 20.04 becomes a more straightforward task. Don’t hesitate to revisit your connections after troubleshooting and adjusting the necessities as detailed in this post.



With clear steps and adjusted code snippets, you can now tackle the QSqlDatabase not connecting issue efficiently! Happy coding!