• the names of the tables and their fields.
• data types of all the fields
• any field formatting information
• field validation details.
• any relationships between the tables.

An example of a query language is SQL (Structured Query Language).

An example SQL instruction would be :

SELECT Pupil.Surname, Pupil.Forename, Pupil.Frm, Pupil.Yr FROM Pupil
WHERE ((Pupil.Frm="G") AND (Pupil.Yr="12"))
ORDER BY Surname;

The DBMS (Database Management System) is a program which allows
the user access to data.

It must...

• allow users  to create and edit the data and provide facilities
  to search the data using a query language.
• allow other applications to use the data.
• create and maintain the data dictionary
• maintain the integrity of the database. On a multi-access system,
  this is done by locking a record or table when a user is editing it.
  This means that another user is unable to edit it at the same time.
  When the data is saved it is unlocked.
• check passwords of individual users and only allow that user access to
  certain parts of the database.
• ensure that recovery is possible if the database is corrupted.

The database administrator is the person responsible for maintaining
the database, including...

• designing the database
• keeping users informed of changes
• maintenance of the data dictionary for the database
• implementing database security measures
• allocating passwords
• providing training to users
• ensuring adequate backup procedures.