(...) The database manager does whatever lookups and calculations the query specifies, returning the results in a tabular form that we can then use as a starting point for further queries.
Queries are written in a language called SQL, which stands for “Structured Query Language”. SQL provides hundreds of different ways to analyze and recombine data. We will only look at a handful of queries, but that handful accounts for most of what scientists do.
Changing database managers
Every database manager — Oracle, IBM DB2, PostgreSQL, MySQL, Microsoft Access, and SQLite — understand SQL but stores data in a different way, so a database created with one cannot be used directly by another. However, every database manager can import and export data in a variety of formats (including SQL), so it is possible to move information from one to another.
The tables below show the database we will use in our examples: