1 SQL Structured Query Language

Short Description
SQL uses the terms table, row, and column for relation, tuple, and attribute, respectively. In. this tutorial we will use the terms interchangeably. …

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1 SQL - Structured Query Language
1.1 Tables
In relational database systems (DBS) data are represented using tables (relations). A query
issued against the DBS also results in a table. A table has the following structure:
Column 1 Column 2 . . . Column n
?. Tuple (or Record)
. . . . . . . . . . . .
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.
SQL uses the terms table, row, and column for relation, tuple, and attribute, respectively. In
this tutorial we will use the terms interchangeably.
A table can have up to 254 columns which may have different or same data types and sets of
values…