Database Glossary

database: A collection of related information stored in a structured format. A database is technically different from a table. A table is a single store of related information; a database can consist of one or more tables of information that are related in some way. For instance, you could track all the information about the students in a school in a students table. If you then created separate tables containing details about teachers, classes and classrooms, you could combine all four tables into a timetabling database. Such a multi-table database is called a relational database.

data entry: The process of getting information into a database, usually done by people typing it in by way of data-entry forms designed to simplify the process.

dbms: Database management system. A program which lets you manage information in databases. Microsoft Access is a DBMS, although the term is often shortened to ‘database’. So, the same term is used to apply to the program you use to organize your data and the actual data structure you create with that program.

field: Fields describe a single aspect of each member of a table. A student record, for instance, might contain a last name field, a first name field, a date of birth field and so on. All records have exactly the same structure, so they contain the same fields. The values in each field vary from record to record, of course.

flat file: A database that consists of a single table. Lightweight database programs such as the database component in Microsoft Works are sometimes called ‘flat-file managers’ (or list managers) because they can only handle single-table databases. More powerful programs, such as Access, can handle multi-table databases, and are called relational database managers, or RDBMSs.

foreign key: A key used in one table to represent the value of a primary key in a related table. While primary keys must contain unique values, foreign keys may have duplicates. For instance, if we use student ID as the primary key in a Students table (each student has a unique ID), we could use student ID as a foreign key in a Courses table: as each student may do more than one course, the student ID field in the Courses table (often shortened to Courses.student ID) will hold duplicate values.

key field: Key fields are also used in relational databases to maintain the structural integrity of your tables, helping you to avoid problems such as duplicate records and conflicting values in fields (see primary key and foreign key).

normalisation: The process of structuring data to minimise duplication and inconsistencies. The process usually involves breaking down a single table into two or more tables and defining relationships between those tables.

primary key: A field that uniquely identifies a record in a table. In a students table, for instance, a key built from last name + first name might not give you a unique identifier (two or more Jane Does in the school, for example). To uniquely identify each student, you might add a special Student ID field to be used as the primary key.

query: A view of your data showing information from one or more tables. For example, you could query a Students database asking "Show me the first and last names of the students who take both history and geography and have Alice Hernandez as their advisor". Such a query displays information from the Students table (firstname, lastname), Courses table (course description) and Advisor table (advisor name), using the keys (student ID, course ID, advisor ID) to find matching information.

rdbms: Relational database management system. A program which lets you manage structured information stored in tables and which can handle databases consisting of multiple tables.

record: 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.

relational database: A database consisting of more than one table. In a multi-table database, you not only need to define the structure of each table, you also need to define the relationships between each table in order to link those tables correctly.

report: A form designed to print information from a database (either on the screen, to a file or directly to the printer).

SQL: Structured Query Language (pronounced sequel or ess-queue-ell). A computer language designed to organize and simplify the process of getting information out of a database in a usable form, and also used to reorganize data within databases.

table: A single store of related information. A table consists of records, and each record is made up of a number of fields. You can think of the phone book as a table: It contains a record for each telephone subscriber, and each subscriber’s details are contained in three fields – name, address and telephone.