In relational database systems (DBS) data are represented using tables (relations). A query issued against the DBS also results in a table.
A table is uniquely identified by its name and consists of rows that contain the stored information, each row containing exactly one tuple (or record).
A table can have one or more columns.
A column is made up of a column name and a data type, and it describes an attribute of the tuples.
The structure of a table, also called relation schema, thus is defined by its attributes.
The type of information to be stored in a table is defined by the data types of the attributes at table creation time.
