Putting it all together Dynamic Data Base Access Norman White Stern School of Business

Beyond 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 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

Example Active 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 Example Hello.asp – What Day is it? – Hello, Today is Bye

ASP Database Access Results <% SQL = “SELECT * FROM CUSTOMERS;” Set DBOBJ = server.createobject(“adodb.connection”) Dbobj.open=“dsn=nwind;uid=;pid=;” Set oRS = DBOBJ.execute(SQL) %>

Continued Customers

Output Customers – Id1, Company1 – Id2, Company2 – … – Idn, CompanyN

How do we handle FORMs in ASP GET form – Var = REQUEST.QUERYSTRING(“field”); Eg <% userid = request.querystring(“userid”) Response.write( “Your userid is “ & userid %> REQUEST.FORM returns POST parameters – Retrieves the userid field from the form for usage in the ASP program

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

example 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 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 Applications Add a song Add an artist Delete a song Delete an artist Update a song

Conclusion Simple ASP files can be very powerful WEB code doesn’t grow as data grows Once 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 Languages Which support DB Access ASP (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 side 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 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….

PHP PHP is more powerful than ASP, and has direct support for a number of major databases PHP runs on almost all web servers PHP is free! Downside is documentation is weak, and the programming environment complex. Better for big, complex projects

Simple PHP Program PHP Test "; ?> OR –

Cold 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 environments Java Servlets Java Server Pages We will talk about these later in the course, but they allow reusable components and a write once run anywhere environment.