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SQL Anywhere 11.0.0 » SQL Anywhere 11 - Introduction » Working with Databases » Overview of data management technologies » Relational database concepts


Database tables

In a relational database, all data is held in tables, which are made up of rows and columns.

A database containing several tables.

Each table has one or more columns, and each column is assigned a specific data type, such as an integer, a sequence of characters (for text), or a date. Each row in the table has a single value for each column.

For example, a table containing employee information can look like the following:

EmployeeID Surname GivenName Phone
102 Huong Zhang 1096
10693 Donaldson Anne 7821
Characteristics of relational tables

The tables in a relational database have some important characteristics:

  • There is no significance to the order of the columns or rows.
  • Each row contains one and only one value for each column, or contains NULL, which indicates that there is no value for that column.
  • All values for a given column have the same data type.

The following table lists some of the formal and informal relational database terms describing tables and their contents, together with their equivalent in non-relational databases such as dBase and FoxPro. This document uses the informal terms.

Informal relational term Formal relational term Non-relational term
Table Relation File
Column Attribute Field
Row Tuple Record
What do you keep in each table?

Each table in the database should hold information about a specific kind of thing, such as employees, products, or customers.

By designing a database this way, you can set up a structure that eliminates redundancy and the possible inconsistencies caused by redundancy. For example, both the sales and accounts payable departments might enter and look up information about customers. In a relational database, the information about customers is stored only once, in a table that both departments can access.

See Designing and creating your database.