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ECommerce >>
Database Concepts
What is a database?
Many of the terms used in
databases have been taken from the traditional filing system. In a
traditional filing system, data was stored in files e.g. payroll file,
customer file etc. Each of these files contains a number of records; the
customer file would contain a record for each customer. Each record
contained a number of fields to store data such as Name, Address and
Telephone number.
Modern database systems are a
collection of tables, which are linked via relationships. Each table is made
up of fields that define the type of data that you want to store in the
table. Each table contains data held in records; a table can have zero
records up to millions of records. The database is stored on computer media
using a filing system.
Tables - Tables are set up to store data on a particular type of data. For
instance you might have a table containing customer details, a table
containing stock and so on.
Fields - Each table contains a number of fields that define the type of data
that the table will hold. The main types of data are numeric and text, but
modern databases usually have a large list of more defined data types. For
instance instead of numeric you can set the data type as currency and so on.
You can limit the size of these fields, which helps to keep the overall size
of the database to a minimum.
Records - Each table will contain a number of records. These records contain
the actual data. For instance a stock table would have a separate record for
every item of stock. These records can be altered, deleted and added to. |
