Programming Python, 3rd Edition

Step 1: Representing Records

If we’re going to store records in a database, the first step is probably deciding what those records will look like. There are a variety of ways to represent information about people in the Python language. Built-in object types such as lists and dictionaries are often sufficient, especially if we don’t care about processing the data we store.

Using Lists

Lists, for example, can collect attributes about people in a positionally ordered way. Start up your Python interactive interpreter and type the following two statements (this works in the IDLE GUI, after typing python at a shell prompt, and so on, and the >>> characters are Python’s prompt—if you’ve never run Python code this way before, see an introductory resource such as O’Reilly’s Learning Python for help with getting started):

>>>bob = ['Bob Smith', 42, 30000, 'software']
>>> sue = ['Sue Jones', 45, 40000, 'music']

We’ve just made two records, albeit simple ones, to represent two people, Bob and Sue (my apologies if you really are Bob or Sue, generically or otherwise^[*]). Each record is a list of four properties: name, age, pay, and job field. To access these fields, we simply index by position (the result is in parentheses here because it is a tuple of two results):

>>>bob[0], sue[2]             # fetch name, pay
('Bob Smith', 40000)

Processing records is easy with this representation; we just use list operations. For example, we can extract a last name by splitting the name field on blanks and grabbing the last ...