1.1 Relational model Flashcards
Database Model
Coceptual
Framework for database systms
3 parts of Database model
- Data Structures
- Operations
- Rules
Data Structures
Prescribe how data is organized
Operations
Manipulate Data structures
Rules
Govern Valid Data
relational model
A database model based on a tubular data structure
big data
unprecedented data volumes and rapidly changing data structures
set
unordred collection of elements enclosed in braces
Ex: {a,b,c}
tuple
Orderd collection of elements enclosed in a parentheses (also known as a row)
table
Has a n ame, a fixed tuple of columns, and a varying set of rows
Column
has a name and a data type
row
an unnamed tuple of values.
Each value corresponds to a column and belongs to the columns data type
data type
a named set of values, from which column values are drawn
select
selects a subset of rows of a table
Project
eliminates one or more columns of a table.
product
lists all combinations of rows of two tables
join
combines two tables by comparing related columns
