This example shows how you can connect to a database from a PyQt application.
The screenshot shows a table of project data that comes from a SQL database. One of the projects is real ;-) (Though the income is made up.)
There are many different database systems: MySQL, PostgreSQL, etc. For simplicity, this example uses SQLite because it ships with Python and doesn't require separate installation.
The default way of connecting to a database in Python is the Database API v2.0. You can see an example of its use in initdb.py. Essentially, you use .connect(...) to connect to a database, .cursor() to obtain a cursor for data querying / manipulation, and .commit() to save any changes you made:
import sqlite3
connection = sqlite3.connect("projects.db")
cursor = connection.cursor()
cursor.execute("CREATE TABLE projects ...")
cursor.execute("INSERT INTO projects ...")
connection.commit()
The above code creates the SQLite file projects.db with a copy of the data shown in the screenshot.
Qt also has its own facilities for connecting to a database. You can see this in main.py, where we open the projects.db file created above and display its data:
db = QSqlDatabase.addDatabase("QSQLITE")
db.setDatabaseName("projects.db")
db.open()
model = QSqlTableModel(None, db)
model.setTable("projects")
model.select()
view = QTableView()
view.setModel(model)
view.show()
As in previous examples, this uses Qt's Model/View framework to separate the two concerns of obtaining and displaying the data: We use model to load the database, and view to display it.
To run this example yourself, first follow these instructions. Then invoke python initdb.py to initialize the database. After that, you can execute python main.py to start the sample application.
While we use SQLite here, you can easily use other database systems as well. For instance, you could use PostgreSQL via the psycopg2 library.