**Course Title:** PySide6 Application Development **Section Title:** Integrating Databases with PySide6 **Topic:** Performing CRUD (Create, Read, Update, Delete) operations ### Overview In this topic, you will learn how to perform basic database operations using QSqlDatabase and QSqlQuery in PySide6. We'll cover how to create, read, update, and delete database records. You'll understand how to use these essential concepts to build a robust and interactive PySide6 application. ### Performing CRUD Operations CRUD operations are fundamental to any database-driven application. These operations enable you to interact with the database by creating new records, reading existing ones, updating existing records, and deleting unnecessary records. #### Create Operation To perform a create operation in PySide6, you can use the `QSqlQuery` class to execute an SQL `INSERT INTO` query. Here's an example: ```python from PySide6.QtSql import QSqlDatabase, QSqlQuery # Connect to the database db = QSqlDatabase.addDatabase('QSQLITE') db.setDatabaseName('database.db') db.open() # Create a QSqlQuery object query = QSqlQuery(db) # Prepare the INSERT INTO query query.prepare('INSERT INTO table_name (column1, column2) VALUES (?, ?)') # Bind the values to the placeholders query.bindValue(0, 'Value 1') query.bindValue(1, 'Value 2') # Execute the query query.exec() # Close the database connection db.close() ``` This code inserts a new record into the `table_name` table with the values `Value 1` and `Value 2`. #### Read Operation To perform a read operation in PySide6, you can use the `QSqlQuery` class to execute an SQL `SELECT` query. Here's an example: ```python from PySide6.QtSql import QSqlDatabase, QSqlQuery # Connect to the database db = QSqlDatabase.addDatabase('QSQLITE') db.setDatabaseName('database.db') db.open() # Create a QSqlQuery object query = QSqlQuery(db) # Prepare the SELECT query query.prepare('SELECT * FROM table_name WHERE column1 = ?') # Bind the value to the placeholder query.bindValue(0, 'Value 1') # Execute the query query.exec() # Fetch the result while query.next(): print(query.value(0), query.value(1)) # Close the database connection db.close() ``` This code selects all records from the `table_name` table where `column1` equals `Value 1` and prints the results. #### Update Operation To perform an update operation in PySide6, you can use the `QSqlQuery` class to execute an SQL `UPDATE` query. Here's an example: ```python from PySide6.QtSql import QSqlDatabase, QSqlQuery # Connect to the database db = QSqlDatabase.addDatabase('QSQLITE') db.setDatabaseName('database.db') db.open() # Create a QSqlQuery object query = QSqlQuery(db) # Prepare the UPDATE query query.prepare('UPDATE table_name SET column2 = ? WHERE column1 = ?') # Bind the values to the placeholders query.bindValue(0, 'New Value 2') query.bindValue(1, 'Value 1') # Execute the query query.exec() # Close the database connection db.close() ``` This code updates the `column2` value to `New Value 2` where `column1` equals `Value 1` in the `table_name` table. #### Delete Operation To perform a delete operation in PySide6, you can use the `QSqlQuery` class to execute an SQL `DELETE` query. Here's an example: ```python from PySide6.QtSql import QSqlDatabase, QSqlQuery # Connect to the database db = QSqlDatabase.addDatabase('QSQLITE') db.setDatabaseName('database.db') db.open() # Create a QSqlQuery object query = QSqlQuery(db) # Prepare the DELETE query query.prepare('DELETE FROM table_name WHERE column1 = ?') # Bind the value to the placeholder query.bindValue(0, 'Value 1') # Execute the query query.exec() # Close the database connection db.close() ``` This code deletes all records from the `table_name` table where `column1` equals `Value 1`. ### Practical Takeaways * Use `QSqlQuery` to execute SQL queries. * Use `QSqlDatabase` to connect to a database. * Use prepared statements to prevent SQL injection. * Use parameter binding to replace placeholders in queries. ### Conclusion In this topic, we covered performing CRUD operations in PySide6. You learned how to create, read, update, and delete database records using the `QSqlQuery` class. You also learned how to use prepared statements and parameter binding to make your database interactions safer and more efficient. ### What's Next In the next topic, you'll learn how to display database data in views using `QTableView`. If you have any questions or need help, leave a comment below.