CIS 451: ASP.NET & Databases

Dr. Ralph D. WestfallFebruary, 2009

What Is a Database? "shared collection of logically

related data" "designed to meet needs of

multiple users" McFadden & Hofer, 1994

Database Advantages less redundant than separate

application files consistency of data integration of data data sharing easier application development scalability e.g., Oracle product line

Databases Advantages - 2 better security, privacy, integrity

controls standardization e.g., field names data accessibility and

responsiveness data independence reduced program maintenance

e.g., centralized validation

Database Advantages - 3 more efficient technology than most

"third generation" application programs powerful code to access items, search

and sort data storage optimization (disk,

memory) efficient updating: add, change, delete

Databases - Disadvantages use more resources than file-based

systems hardware, software

require specialized personnel potential data access conflicts

operations vs. data mining potential organizational conflicts incompatibilities between

database systems

Universal Data Access ODBC: open database connectivity

standard API for accessing relational databases

API = application programming interface

"drivers" for Access, dBase, DB2, Excel, text, etc.

Microsoft is a leading ODBC backer and ships its own version with Windows

Universal Data Access - 2 OLE-DB: DB object linking &

embedding accesses relational databases through

ODBC accesses other data also

files, spreadsheets, e-mail, video, voice, images, web pages, object databases, etc.

data is accessed "in place" (no need to load into a database)

OLE-DB Concepts data store = "persistent" collection

of data data provider = gets data from data

store OLE-DB "driver" for database, email

data, etc. data consumer = application that

uses data ADO.NET (ActiveX Data Object)

interfaces to data store through OLE-DB

ADO.NET ADO stands for ActiveX Data

Objects part of Microsoft's OLEDB strategy to

enable programs to almost any kind of data on a computer

provides objects to easily connect to a variety of data sources

databases, mail servers, http servers, Excel documents, etc.

Using Databases with Internet web browser interface very easy to use

compatible with all kinds of hardware Internet is global low cost delivery to large # of users multimedia capabilities ASP.NET can access data through ADO

and OLE-DB for web applications

ADO.NET Model Objects Connection: to a specific file or

server Command: holds/runs SQL/other

text to query/update data, call stored procedures, etc.

DataReader: high-speed, limited function interface between database and application

ADO.NET Model Objects - 2 Data Adapter

uses SQL commands to transfer data back and forth between the application and the database

DataSet not connected to database

but data can be changed and uploaded

contains one or more DataTables can "join" multiple tables in DataSet

ADO.NET Model Objects - 3 DataTables have the following:

DataRowCollection - rows DataColumnCollection - fields DataView - use this if need to sort

data that is used as a datasource for an object e.g., a datagrid

Database Design determine functional requirements identify data required for

applications organize the data

tables (usually normalized) relationships between tables

identify business rules (middle tier) design queries and applications

Key Fields each row in a table is uniquely

identified by one or more key field(s)ID# Name City322 Karim Pomona

Dr# Patient# Appointment397 0246875 10/24/00 2 PM 'key field(s) underlined

Rules for Tables in a Database all items in each table should relate to one

main topic or subject, on a one-to-one basis employees: SS#, Name, Address, Hourly Pay paychecks: SS#, Date, Pay Amount

tables should be "normalized" (2NF or more) no repeated information no fields that may be intentionally empty no fields with data that can be calculated

(derived) from other fields

Normalization splitting tables to avoid problems

avoid duplicated data and empty cells avoid problems: add, change or delete

dataSID Name GWE Class Quarter Grade

322 Ana No C101 F99 pass

322 Ana No C234 S00 A use 2 tables instead

1-SID, Name, GWE; 2-SID, Class, Quarter, Grade

Normalization - 2 library has borrowers, books, circulation

put circulation in borrowers file? repeating patron data for every checked out

bookBorrower#, Name, Address, Book# or repeating (often empty) columnsBorrower#, Name, Address, Bk#1, Bk#2, etc.

normalize: separate borrowers, circulationBook #, Title, Author, Year, etc.

Patron#, Name, Address, etc.

Patron#, Book#, Due Date

Specialized Normalized Tables "parent-child tables"

building: name, address, land area floor: #, common (non-rentable) area

room: #, square feet parent table has family name, address

family member table has first names, DOB, gender

"lookup table" zip, city, state

zip code "determines" city and state data storage only needs zip

Cerritos mail used to be addressed to Artesia

Denormalization sometimes more efficient to not

completely normalize all tables less normalization can increase

efficiency and possibly reduce number of tables

e.g., 1 customer table with fields for 2 voice phone numbers

only need to update 1 table don't need to do a join to get all phone

#s

Denormalization - 2 "do not store data in a table if it can

be calculated from other data" e.g., total field (in a separate table) but with a total field don't need to total

a large # of records every time need a total

but do need extra code to update totals when records are added, changed or deleted (as in a "getter" in OO code)

Indexes data is added to database in random order more efficient processing for searches and

sorting (less efficient for adding data) index table has sort order (stores position)

Data File Order Index/OrderJose (1) 1 (4)Phuong (2) 2 (3)Gunther(3) 3 (1)Ahmed (4) 4 (2)

Creating a Database or Table using SQL commands with ADO in

VB.NET using VB.NET Server Explorer using SQL Server Management

Studio using "3rd party" programs

similar to Server Explorer approach or more sophisticated

Creating a Database in Access Access 2003 new database options

Design View user needs to type in Field Name,

select Data Type, input Field Size and other properties

wizard that provides common templates entering data manually

uses default settings (like a spreadsheet)

Create Database in Access - 2 could use File>Get External

Data>Import to pull in data from a file, other databases, spreadsheets, etc. could go into a new table, or be added

to an existing table need to set field properties when

bringing in data to a new table e.g., Field Name, Data Type, etc.

SQL Server and Express Microsoft's SQL Server is designed to

handle very large scale applications more security, transaction logging , stored

procedures, very many users, etc. MSDE (Microsoft Data Engine) is the

software that runs SQL Server database the "engine" in Access is Jet 4.0 (currently) but Access can read/write MSDE databases

Create SQL Server Express DB install SSE 2008 load external data as with SQL

Server Management Studio

Using Server Explorer with SSE

View>Server Explorer in VB.NET click Servers>SQL Servers right click server that ends with \

NETSDK click (expand) new database right click Tables>New Table

Using Server Explorer to Create SQL Server Express Database

add fields to master type in Column Name type/select Type, Length, etc. File>Close or right click tab>Close

after enter last field File>Save Table1 and replace name

in Choose Name input box

Stored Procedures code to manipulate database (retrieve data,

add, change, delete) stored in database like subroutine, can use in multiple

programs (but not with Access database) less storage: once instead of multiple

copies easier to update than multiple copies stored queries run faster inside database easier to migrate to other platforms or

scale up to larger volumes