Database lesson

Challenge
No

Goats love databases. They like nothing better than writing SQL queries.

Cthulhu teaches an SQL class. It had an idea for improving a lesson. It gave some goats the old lesson, then a test (the "before" test), then the new lesson, then another test (the "after" test). What happened to the scores?

Download the starting worksheet with the data. It's like this:

Start

Notice that scores can go down. That's normal; scores have some randomness to them.

Each record has three values:

  • Name. Cannot be empty.
  • Before. Number, zero or more.
  • After. Number, zero or more.

Some data might not fit the rules. You'll need to validate it.

Write a program to compute averages and counts. Here's the output.

Output

Your program should warn the user if more than 10% of the records are invalid. Don't forget to remove the message each time the program runs.

Upload your solution. The usual standards apply.

Where referenced