21.13. Debugging

One common pattern when you are developing a Python program to connect to an SQLite database will be to run a Python program and check the results using the Database Browser for SQLite. The browser allows you to quickly check to see if your program is working properly.

Q-1: True or False? You can connect multiple programs to a SQLite database.

• True
• It is common to connect a Python program to an SQLite database, while using the Database Browser for SQLite at the same time.
• False
• Try again!

You must be careful because SQLite takes care to keep two programs from changing the same data at the same time. For example, if you open a database in the browser and make a change to the database and have not yet pressed the “save” button in the browser, the browser “locks” the database file and keeps any other program from accessing the file. In particular, your Python program will not be able to access the file if it is locked.

Q-2: True or False? SQLite will allow two programs change the same data at the same time.

• True
• Try again!
• False
• SQLite takes care to keep two programs from changing the same data at the same time, so make sure you save frequently!

So a solution is to make sure to either close the database browser or use the File menu to close the database in the browser before you attempt to access the database from Python to avoid the problem of your Python code failing because the database is locked.

Q-3: True or False? SQLite will lock a database if it has been changed and saved in a program.

• True
• Try again!
• False
• SQLite will lock a database if it has been changed and not yet saved in a program, and you have tried to access it in another program.

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