Section 1
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Other client/server system architectures
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Section 1
(50 cards)
Other client/server system architectures
Application servers store business components. Web servers store web applications (designed to run on a web server) and web services (like web applications, designed to run on a web server).
Composite Primary Key
Primary key uses two or more columns.
Hierarchial Database Model
the data elements at one level "own" the data elements at the next lower level. - Limited to a one-to-many relationships called parent/child relationships - not as easy to use as relational databases.
Wide Area Network (WAN)
A network that connects devices in geographically separated areas. Two or more LANs (local area network) can connect, and/or an individual system and LAN can connect and share data over larger private networks.
nchar, nvarchar
A string of letters, symbols, and numbers in the Unicode character set
Null Value
A special field value, distinct from zero, blank, or any other value, that indicates that the value for the field is missing or otherwise unknown.
Table
An arrangement of data made up of horizontal rows and vertical columns.
Server
a computer with enough processor speed, internal memory (RAM), and disk storage to store the files and databases of the system and provide services to the clients of the system. Referred to as a database server.
Rows
Contains a set of values for a single instance of the entity
float, real
floating-point values that contain an approximation of a decimal value
Enterprise Systems
When a system consists of networks, mid-range systems, and mainframe systems. Provide enterprise wide support and data access.
Database Management System (DBMS)
A system for managing data that allows the user to store, retrieve, and analyze information. Microsoft SQL Server is a DBMS and is referred to as the back end. DBMS does the back-end processing.
How do web applications work?
- Web browser on a client sends a request to a web server. - The web server process the request - Web server passes any request for data to the database server - Database server returns the results to the web server - Web server returns the response to the client's browser
bit
A contraction of "Binary Digit". - A bit is the single unit of information in a computer, typically represented as a 0 or 1. - Can represent a true or false value
char, varchar
A string of letters, symbols, and numbers in the ASCII character set
datetime, smalldatetime
alphanumeric data that represents a date and time. Various formats are acceptable.
data access API (application programming interface)
It provides the interface between the application program and the DBMS.
Primary key
Unique identifier of each row in the table Usually a single column, but it can be multiples (composite primary key)
Non-Primary key
Unique keys that identifies each row in a table.
Object Database
An object database, also called an object-oriented database, stores data as objects, which can be grouped into classes and defined by attributes and methods - common with object-oriented programming languages such as C#, C++, and Java
Cell
Intersection of a row and a column is a cell. It stores a single value.
Network Database
-A collection of physically linked records in a one-to-many relationship in which a member (child) can have more than one owner (parent) -a database where records can be networked to other records through paths that are different from the hierarchy itself
Microsoft API
ADO.NET Communicates directly with SQL server.
First database released
Oracle 1979 DB2 1985 MySQL 2000 SQL Server 1987
front-end processing
The processing done by the client software. The client is the front end.
network operating system (NOS)
The operating system that runs a network, steering information between computers and managing security and users
Clients
Computers, such as users' personal computers, that use any of the services provided by servers. PCs, Macs, or workstations of the system
decimal, numeric
Decimal values that are accurate to the least significant digit. The values can contain an integer portion and a decimal portion.
money, smallmoney
monetary values that are accurate to four decimal places
Client-Server System
processing is divided between client and server
Local Area Network (LAN)
a computer network that covers a small area. A simple client-server system.
How standard SQL does not help you?
Any non-trivial application will require modifications when moved from one SQL database to another.
Foreign key
A primary key of one table that appears an attribute in another table and acts to provide a logical relationship among the two tables. A table may contain more than one foreign keys. When you define a foreign key for a table in SQL, you cannot add rows to the table with the foreign key unless there is a matching primary key in the related table.
SQL Query
A command created using SQL database client software. The queries are passed to the DBMS through the API. Afterwards the DBMS interprets the query and sends the results back to the client.
One-to-many relationship
A relationship between two tables in a database in which one record in the primary table can match many (zero, one, or many) records in the related table. - The most common type of relationship.
File-Handling System
All of the processing is done on the clients
Network
Cables, communication lines, and other components that connect the clients and the servers of the system.
Why does SQL server use data types?
The data type assigned to a column determines the type and size of the information that can be stored in a cell.
Index
An efficient way to access data from a table based on the value in specific columns. An index is automatically created for a table's primary and non-primary keys
Application Software
Computer software created to allow the user to perform a specific job or task. Application software does the work that the user wants to do.
Primary platforms
Oracle is used for large, mission-critical systems that run on one or more Unix servers. Released 1979 - Unix/Linux - z/OS - Windows - Mac OS DB2 for large, mission-critical systems that run on legacy IBM mainframe systems. Released 1985 - OS/390, z/OS, and AIX - Unix/Linux - Windows - Mac OS MySQL is an open-source database that runs on all major operating systems and used for web applications. Released 2000 - Unix/Linux - Windows - Mac OS SQL Server used for small to medium-sized systems that run on one or more Windows servers, releasing a Linux version - Windows (1987) - Linux (2017)
Relationships
In a relational database, relationships exist between the primary key in one table and the foreign key of another table, and between a unique key in one table and a foreign key in another table.
Columns
Represent some attribute of the entity
int, bigint, smallint, tinyint
Integer values of various sizes.
relational database
A database that represents data as a collection of tables in which all data relationships are represented by common values in related tables
How standard SQL helps you?
- Basic SQL statements are the same for all SQL dialects - Easy to learn other dialects
one-to-one relationship
In databases, a relationship in which each record in Table A can have only one matching record in Table B, and vice versa.
Default Value
A value a field will assume unless an explicit value is entered for that field.
Identity Column
A numeric column whose value is generated automatically when a row is added to the table. - Estimate using the Is Identity, Identity Seed, and Identity Increment properties.
Many-to-many relationships
Relationships involving two entity types in which an instance of one type can relate to many instances of the second type, and an instance of the second type can relate to many instances of the first. It can be broken down into two one-to-many relationships.
Section 2
(36 cards)