Tutorial:
Database - PHP - RealPath Connections
Dr.
Thomas E. Hicks
Computer Science
Department
Trinity University
Once you have a working web server, one may connect to the server
There are times one must move a database to another folder or another drive. With an ODBC connection, one simply changes the interface connection and all is done. The problem is that the ODBC connection requires administrative access. Since normal users may not create or change such connections, this is often not an available option to those maintaining web sites.
When a database is moved with a RealPath connection, each and every page
interfacing with the database must be individually changed/altered to reflect
the new location. This is much more of a hassle than ODBC connections, but it
makes database interface possible to those leasing web site space on a
commercial Internet Service Provider (ISP) This often makes it possible
for students to do database interface on a university web server; the
administration is not going to provide or manage ODBC for the students. This
often makes it possible for small companies to do database interface on an ISP
web server; the ISP is not going to provide or manage ODBC for the customers.
This often makes it possible for teachers to do database interface on a school
web server; the administration is not going to provide or manage ODBC for the
teachers.
Both connection types have advantages and disadvantages. It is the purpose of this paper to describe the RealPath option. You may find out information about ODBC connections with the following tutorial:
Database - PHP - ODBC Connections
In order to use ODBC to enable web pages to update and query a database, the host computer must be running web server software. One of the Tutorials below might help you install web server software on your computer.
IIS 5 Install on Windows XP Pro
IIS 5 Installation on Windows 2000 Pro/Server
It might even help to read a tutorial that describes the need for Database Web Applications.
Database Need For Web Applications
The Security Database is opened and the Tables tab is selected; in order to keep our example simplistic, the Security Database has only a single table, called Users. The contents of our very simple Users table can be seen below.
Each record in the Users table contains fields Name, No, Password, and IDNo; these will be needed later.
The datatypes of each field may be seen below.
The Security Database above was is ultra trivial application which had only one database table. Relational databases often have many tables; this is true of Access databases as well. This database may be downloaded.
The customers table stores the video store customer entity. The Movie table stores the video store movie entity. The Video Database is a relational database; the Transact table stores the relationship of movies checked out by the customers.
The Customer.dbf table contains 24 records. Each record of the customer table contains fields Name, No, and Phone. The table designer view shows the datatypes associated with the customer fields.
The Movie.dbf table contains 38 records. Each record of the customer table contains fields Name, No, and Category. The table designer view shows the datatypes associated with the movie fields.
The Transact.dbf table contains 101 records. Each record of the transact table contains fields Name, No, and Phone. The table designer view shows the datatypes associated with the customer fields.
This database may be downloaded.
In order to configure ODBC, one must have administrative privileges. All users using Windows 98 have administrative privileges. Windows NT, Windows 2000, and Windows XP can be configured for individual log in accounts; in order to set up ODBC on these configurations, one must have administrative privileges.
RealPath connections require no administrative privileges.
File adodb.inc.php includes many of the database PHP4 extensions to php. File adodb-time.inc.php is used by adodb.inc.php. These should be placed in the web site. I have chosen to place them in directory ADODB for purposes of this tutorial..
There is PHP support for many databases; among them are Oracle, informix, mysql, ibase, cvc, postgres, sybase, foxpro, etc. Each of these shall require its own driver. Although you shall not neeed all of the drivers, I have placed a collection that I downloaded from the Internet in directory Drivers. See Below! These should be placed in the web site. I have chosen to place them in directory ADODB for purposes of this tutorial..
You might want to download your own files from the Internet, but for sake of simplicity, I have included those used in the tutorial in the zipped file below; place them in a folder, called ADODB, at the root of your IIS directory. (See Below!)
The PHP files should be placed in the web site. For purposes of this tutorial,
all of the PHP demonstration files shall be placed in directory PHP at the root
of the IIS directory. See Below!
The ODBC applet can be found in the control panel. Using the mouse, double-double click on ODBC. (See Below!)
We are going to place all of the PHP files in folder C:\Inetpub\wwwroot\PHP. We could place the database files anywhere on the drive. For security reasons, it is not a good idea to place them in the wwwroot directory.
For purposes of this tutorial, we shall assume that the Video database files are located in C:\Video. For purposes of this tutorial, we shall assume that the Security database is located in C:\.
#------------------------------------------------------------------------- ' Establish RealPath Connection To The Server #------------------------------------------------------------------------- ' Unsuccessful Thus Far! |
The PHP code to connect to the Access Security database is as follows:
#--------------------------------------------------------------------------
# Include The Database Utilities
#--------------------------------------------------------------------------
Include('../adodb/adodb.inc.php');
#--------------------------------------------------------------------------
# Access Database ODBC Connect To The Server
#--------------------------------------------------------------------------
$Conn = New COM("ADODB.Connection");
# --------------------- Connection With Absolute Path ---------------------
$ConnStr = "DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=" .
RealPath("C:\Security.mdb");
# --------------------- Connection With Relative Path ---------------------
$ConnStr = "DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=" .
RealPath("../../../Security.mdb");
$Conn->Open($ConnStr);
|
Not quite as simple as the ODBC, but it does not require administrative access. RealPath may be passed either an absolute path or a relative path; examples of both are given above. Because of the relative positioning described above, the location of the databases may be traced three levels up from the current web page.
Although it is not the purpose of this tutorial to teach PHP or HTML, a example is necessary to verify that the connection works.
<?PHP
#=========================================================================
#=========================================================================
#==== ConnectRealPathSecurity.php ====
#=========================================================================
#==== ====
#==== Purpose : Demonstrate RealPath Connection To The Video ====
#==== Database. ====
#==== ====
#==== Written By : Dr. Thomas E. Hicks Date: 08/1/2003 ====
#=========================================================================
#=========================================================================
#--------------------------------------------------------------------------
# Include The Database Utilities
#--------------------------------------------------------------------------
Include('../adodb/adodb.inc.php');
#--------------------------------------------------------------------------
# Access Database ODBC Connect To The Server
#--------------------------------------------------------------------------
$Conn = New COM("ADODB.Connection");
# --------------------- Connection With Absolute Path ---------------------
$ConnStr = "DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=" .
RealPath("C:\Security.mdb");
# --------------------- Connection With Relative Path ---------------------
$ConnStr = "DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=" .
RealPath("../../../Security.mdb");
$Conn->Open($ConnStr);
#--------------------------------------------------------------------------
# Read All Of The User Names Into The RecordSet
#--------------------------------------------------------------------------
$UserSQL = ' SELECT Name ' .
' FROM Users';
$RecordSet = $Conn->Execute($UserSQL);
$Name = $RecordSet->Fields(0);
While (!$RecordSet->EOF)
{
Echo $Name->Value . '<BR>' ;
$RecordSet->MoveNext();
}
#--------------------------------------------------------------------------
# Close & Terminate The Connections
#--------------------------------------------------------------------------
$RecordSet->Close();
$Conn->Close();
$RecordSet = null;
$Conn = null;
?>
</BODY></HTML>
|
You can see the results below:
