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together together Dynamic Data Base Dynamic Data Base Access Access Norman White Stern School of Business
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Putting it all togetherPutting it all togetherDynamic Data Base AccessDynamic Data Base Access
Norman White
Stern School of Business
Beyond MultimediaBeyond Multimedia
Question– How do I add the capability to query/update a data base from a
WEB page Answers
– Need a Client/Server data base Oracle, SQL Server tec.
– Need tools to access data base Active Server pages PERL JAVA (JDBC) Java Servlets Cold Fusion Etc…
Data Driven WEB PagesData Driven WEB Pages
Many business applications depend on knowledge of the current environment which is often available in a database somewhere
Need to “WEB-Enable” applications, so customer, supplier etc. can interact directly with a companies database.
Database changes are automatically immediately available on web site
ExampleExampleActive Server PagesActive Server Pages
ASP files are Visual Basic or Java programs which can be mixed with HTML
The WEB server executes the ASP code as it generates the WEB page.– Code runs on the Server side, client never sees it– Code can dynamically access/update one or more
databases Only runs on Microsoft web servers, but similar
applications run cross platform (PHP, Cold Fusion, Java Servlets etc.)
Simple ASP ExampleSimple ASP Example
Hello.asp– <html><head><title>What Day is it?</title></head>– <body>– <script language=“vbscript” runat=“server>Hello, <P><% datToday = Date() %>
Today is <% =datToday %> <P>Bye</body></html>
ASP Database AccessASP Database Access
<%@ language=“vbscript” %> <html><head><title>Results</title></head> <body> <% SQL = “SELECT * FROM CUSTOMERS;” Set DBOBJ =
server.createobject(“adodb.connection”) Dbobj.open=“dsn=nwind;uid=;pid=;” Set oRS = DBOBJ.execute(SQL) %>
ContinuedContinued
<P>Customers</p> <table border= 3> <% while not oRS.EOF %> <TR> <TD> <% =oRS.Fields(“CUSTOMERID”).Value %> </TD> <TD> <% =oRS.Fields(“COMPANYNAME”).Value %>
</TD> </TR> <% oRS.Movenext %> <%WEND %> </table> </body></html>
OutputOutput
Customers– Id1, Company1– Id2, Company2– …– Idn, CompanyN
How do we handle FORMs in How do we handle FORMs in ASPASP
GET form– Var = REQUEST.QUERYSTRING(“field”);
Eg <% userid = request.querystring(“userid”) Response.write( “Your userid is “ & userid %> REQUEST.FORM returns POST parameters <% userid =request.form(“userid”) %>
– Retrieves the userid field from the form for usage in the ASP program
But what good is all this?But what good is all this?
Things get interesting if some of the fields in my database contain links to URLs
Now I can have a database that maintains information about web objects
I can allow user to select certain search characteristics
To update info, I update the database, and the links are automatically generated
exampleexample
You have a music collection of a bunch of mp3 files which you keep adding to. You maintain information about your collection in a database
Your database– Song Table
Artist Id, album name, record label, date of release, type of music,name of song, link to MP3 file
– Artist Table Artist name, bio, link to picture
Your applicationYour application
Web page with form that allows users to choose selection criteria
ASP file processes form and retrieves a list of links that point to songs that satisfy selection
User clicks on link and song plays
Additional ApplicationsAdditional Applications
Add a songAdd an artistDelete a songDelete an artistUpdate a song
ConclusionConclusion
Simple ASP files can be very powerfulWEB code doesn’t grow as data growsOnce built, no maintenance (except for
updating the database, which in many cases is already being done)
Easy to “web enable” existing database applications
Server Side Scripting Server Side Scripting Languages Which support DB Languages Which support DB
AccessAccessASP (Visual Basic, JavaScript) C++ and C#
coming soon.Cold Fusion (CFM files)PhP (Free open source solution, runs on
Unix, Linux, NT) Supports all major databases
PERL DBI (Data Base Interface)Java, Javascript Servlets
How do you identify server How do you identify server side scriptingside scripting
In most cases, the language processors become PART of the WEB browser.
Dramatically reduces overhead involved with running a separate program (ala CGI)
Other AlternativeOther Alternative
JDBC – Java Data Base Connectivity– Allow Java applet to directly connect to a
remote database– Problems ….
Security (java can only connect back to server its code came from)
Overhead for connection(s) across internet Depends on users browser being able to handle java
– Best use is within an intranet….
PHPPHP
PHP is more powerful than ASP, and has direct support for a number of major databases
PHP runs on almost all web serversPHP is free!Downside is documentation is weak, and
the programming environment complex.Better for big, complex projects
Simple PHP ProgramSimple PHP Program
<html><head><title>PHP Test</title></head>
<body> <?php echo "Hello World<P>"; ?> </body></html>OR
– <?php echo $HTTP_USER_AGENT; ?>
Cold FusionCold Fusion
Cold Fusion is a platform independent development system similar to ASP
Some extra features include replication and rollover– You can replicate cold fusion sites for better
performance, and you can have one site back up another site in case one fails.
Other development Other development environmentsenvironments
Java ServletsJava Server Pages
We will talk about these later in the course, but they allow reusable components and a write once run anywhere environment.
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