Database Management

Database
A collection of data.
Database Management System (DBMS)
A software system that provides a set of services on a database.
Relational Database Management System (RDBMS)
A software system that provides a set of services organized around the relational algebra, which is founded on set theory.
Relational schema
the name of a table, its attributes (column names)
Database schema
a set of relation schema
Structured Query Language (SQL)
is composed of three parts:
DDL: Data Definition Language
DML: Data Manipulation Language
DQL: Data Query Language
Data Definition Language (DDL)
the language used to specify the physical structuring of a database
– create
– alter
– drop
Data Model
A conceptual representation of the data structures that are required by a database application.
Super Key
Any attribute or set of attributes that uniquely determines a row of a table
Candidate Key
Any attribute or minimal set of attributes that uniquely determines a row of a table
Foreign Key
An attribute or set of attributes in one table, that form a candidate key in a different table
Index Key (a.k.a search key)
An attribute or set of attributes that serve as the basis of organization of an index structure. Need not be a candidate key.
Primary Index
The index structure that determines the placement of a record on disk
Primary Key
In SQL, index key for the primary index. SQL standard: “Primary Key” stipulates primary key is unique. i.e. it is super key. Primary key declaration is optional.
primary index key
Formal definition of primary index does not require uniqueness of the key.
Surrogate
An instance of a data type that can be used to locate a disk block or a row in a database. Can be a key or row id (RID)
-informally, but never formally a pointer.
Relation
Any subset of a Cartesian product.
Relation schema
the name of the table, its attributes (column names)
– Example 1: Name(First, Last)
– Example 2: T1(a1, …, an)
Database schema
a set of relation schema
– Example 1:
{Name(student-id, First, Last), Class(class-name, student-id)}
– Example 2:
{R(a1, a2, a3), S(b1,b2)
Entity
something that can be identified (named)
Attribute
description of an entity’s characteristics
Identifier
attributes that name, or identify, entity instances
Relationship
associations among entities
Weak entity
those that must logically depend on to another entity for unique identification
Strong entity
has a candidate key
Subtype entity
an entity that represents a special case of another entity, called supertype
Supply Chain
The management of the components, manufacturing and distribution of manufactured commodity. It includes warehousing and tracking inventory.
Supply Chain Integration (SCI)
The free and seamless flow of relevant data up and down the supply chain. It enables supply chain management.
Electronic Data Interchange (EDI)
A form of electronic commerce that supports computer to computer communications. EDI systems provide high speed communication via transfer of files in a standard format between trading partners using secure electronic communication links.
Collaboration
inter-enterprise business process of integration
Index
a data structure used to find data on disk
Access path
a) the choice of an index to find data in a table
b) the sequence of steps or disk blocks accessed to locate data
Index key
the set of attributes on which a database index is organized
Primary index
the basis on which a table is organized on disk
Secondary index
an additional access path beyond the primary index
Dense index
key value and surrogate for every data record that is in the index
Sparse index
not dense
-usually the primary index is this.
Enterprise schema
A data model that federates (integrates) the data model of a large number databases across an organization