UNIT 1 Flashcards
SQL includes commands to create database objects such as tables, indexes, and views, as well as commands to define access rights to those database objects.
data definition language (DDL):
SQL includes commands to insert, update, delete, and retrieve data within the database tables.
data manipulation language (DML)
SQL is a
Non procedural language
A group of database objects—such as tables and indexes—that are related to each other.
Schema
Fixed character length data, 1 to 255 characters
Char
Variable character length data,1 to 2,000 characters.
Varchar
used to specify numbers with two decimal places and up to nine digits long, including the decimal places. Some RDBMSs permit the use of a MONEY or a CURRENCY data type.
Decimal
Integer values only
Int
Small integer values only
Small int
formats vary. Commonly accepted formats are: ’DD-MON-YYYY’, ’DD-MON-YY’, ’MM/DD/YYYY’, and ’MM/DD/YY’
Date
a collection of related data held in a _____ format within a database. It consists of columns and rows.
Table
column or combination of columns whose values uniquely identify each row in the table
Primary key
A column or combination of columns used to establish and enforce a link between the data in two tables
Foreign key
Ensures that no duplicate values are entered in specific columns that do not participate in a primary key
Unique
Enforces domain integrity by limiting the values that are accepted by a column
Check
