Data Base (yellow belt)

Database that works with pairs (date, event).

A set of commands to work with the database

• Add date event — add a pair(date, event) to the database;
• Print — show all database contents;
• Find condition - show all records contained in the database that satisfy the condition;
• Del condition - remove from the database all records that satisfy the condition;
• Last date - display a record with the latest event that happened not later than the date;

How to write a condition

Implemented comparison operators: <, <=, >=, >, ==, !=. A condition may consist of several sub-conditions that are connected by logical OR / AND.

Example:

• Find date < 2017-11-06 - find all the events that happened before November 6, 2017 and show them;
• Del event != "holiday" - remove from the database all events except "holiday".
• Find date >= 2017-01-01 AND date < 2017-07-01 AND event == "sport event" - find all the events "sport event" that occurred in the first half of 2017;
• Del date < 2017-01-01 AND (event == "holiday" OR event == "sport event") - remove from the database all the events "holiday" and "sport event" that happened before 2017.