Database Terminology
- Table
A single store of related information. A table consists of records, and each record is made up of a number of fields. - Record
A table consists of records, and each record is made up of a number of fields. A record contains all the information about a single 'member' of a table. In a students table, each student's details (name, date of birth, contact details, and so on) will be contained in its own record. - Fields
describe a single aspect of each member of a table. A student record, for instance, might contains a last name field, a first name field, a date of birth field and so on. - Key Field
Keys are crucial to a table structure for many reasons, some of which are identified below:- They ensure that each record in a table is precisely identified.
- They help establish and enforce various types of integrity.
- They serve to establish table relationships.
- Primary key will uniquely identify each record. It may or may not provide information about the record it identifies. It must not be Null-able, that is if it exists in a record it cannot have the value Null. It must be unique. It cannot be changed.
- Foreign keys are used to create relationships between tables. A foreign key is a field in a relational table that matches the primary key column of another table. The foreign key can be used to cross-reference tables.
- Referential integrity
is a database concept that ensures that relationships between tables remain consistent. When one table has a foreign key to another table, the concept of referential integrity states that you may not add a record to the table that contains the foreign key unless there is a corresponding record in the linked table. - Database
A collection of information stored in an organized form in a computer. - Database Management System (DBMS)
A program or system of programs that can manipulate data in a large collection of files (the database), cross-referencing between files as needed. - Query
An information request. - Report
A database printout that is an ordered list of selected records and fields in an easy-to-read form.
