The document describes several SQL experiments conducted to create and populate tables, apply constraints, modify schemas, and perform queries. Key points:
1) Tables were created for departments and employees, with data inserted. Describe commands showed the schemas.
2) More tables were created, drop and delete commands were used, and select queries with and without where clauses were run.
3) Schemas were altered by adding columns and modifying data types. Update commands modified existing data.
4) Primary keys, foreign keys, unique constraints and other constraints were applied to newly created tables in various experiments.
5) Select queries used aggregate functions, arithmetic operators, sorting, and nested queries. Joins were performed