Student Information Search Engine

In this example application we create a search engine for student information database. Student's records are stored in a file with a format as follow:

#SSN,Last Name,First Name,Major,GPA,Phone,Email

Run the Example

Click here to run this example.

HTML FORM

Here is the HTML FORM for this example:

<FORM ACTION="cgi-bin/searchEngine.pl" METHOD="POST">
<b>Enter Search Key </b><INPUT TYPE="TEXT" NAME="keyword" SIZE="15"> 
<INPUT TYPE="SUBMIT" VALUE="Search">
</FORM>

searchEngine.pl

The following is the Perl source code:

(1)
#!/usr/local/bin/perl
 ########################################################################
 #  searchEngine.pl--A Student Information Searching Engine
 #  1/6/98 by Zhanshou Yu
 #  Any comments please send to :
 #  zhanshou@hotmail.com
 ######################################################################## 
(2)
# Global variable , locate the database file
$DATABASE= "/home/CGITutorial/students.db";
(3)
# Get the input
read(STDIN,$buffer,$ENV{'CONTENT_LENGTH'});
(4)
#Split the name-value pairs
($keyword,$value)=split(/=/,$buffer);

# Substitute special character to its original character
$value=~ tr/+/ /;
$value=~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;

(5)
#------print the return HTML------------------
#print the MIME type
print"Content-type: text/html\n\n";
(6)
#Check whether missing search key
&missing_field('Search Keyword') unless ($value);

# Initialize match count to -1 to indicate no match.
$count=-1;
(7)
# Open the database file for input
open(DB,"<$DATABASE") || die "Can't open $DATABASE\n";
(8)
# Loop through the database file and look for match
while($inline=<DB>)
 {
   # Remove the line-feed character from each record line
   chop($inline);
   # If keyword is in the current line then we found a match
   if($inline =~ /$value/i) 
   {
     # The following line highlights the keyword in the record using HTML <B> bold
     # tag. This is not essential but makes the output looks good specially since
     # it will show clearly in bold where it found the match. You can comment out
     # this line if you feel this is something you do not want.
     $inline =~ s/$value/<b>$value<\/b>/;

     # Increment match count   
     $count++;
     # Store the matched record in an array.
     @matches[$count] = $inline;
   }
}
# Close the database file.
close(DB);
(9)
# Print the HTML output header 
print "<HTML><HEAD><TITLE>Student Information Search Results </TITLE></HEAD>\n";
print "<BODY BGCOLOR=#FFFFFF>\n";
print "<center><H1> Student Information Search Results</H1></center>\n";

(10)
# If count is greater than zero or equal to zero, we have at least a match
# result that needs to be displayed.
if ($count >= 0 ) 
{
  # Since we start counting from 0, we need to increment it before we print count.
  # This will make it more readable. 
	$count++;

  # Print the count summary and header
  print "The keyword <B> $value </B> matched $count record(s) in the Student Information database.";
  print "These records are as follows:<BR>\n";

  # Now we have to loop through the matches found and extract information from each
  # record and format them for output.
  foreach $record (@matches)
  {
   # Split each record in fields.
	 ($ssn,$last,$first,$major,$gpa,$phone,$email) = split(/,/,$record);

   # Print HTML formatted record
	print "<PRE>\n";
	print "SSN           : $ssn\n";
	print "Last name     : $last\n";
	print "First name    : $first\n";
	print "Major         : $major\n";
	print "GPA           : $gpa\n";
	print "Phone         : $phone\n";
	print "Email         : $email\n";
	print "</PRE><HR>\n";
   }
 }
(11)
 # We didn't find any match so print a sorry message.
 else {
	print "Sorry, the keyword <B> $value </B> did not match any record in the database.Please try again.";
	print "</BODY></HTML>";
 }
(13)
#missing_field subrountine. If mission field, please enter the key word.
 sub missing_field {
  local($variable)=@_;
  print "<html><head><Title>Student Information Search Enginer</Title></head>\n";
  print "<body><center><h1> Student Information Search Enginer</h1></center>\n";
  print "<TABLE BORDER=\"0\" bgcolor=#ffefd5>\n";
  print "<tr><TD>\n";
  #print out Form to enter keyword
  print "<FORM ACTION=\"search.pl\" METHOD=\"POST\">";
  print "<b>Please Enter Search Key </b><INPUT TYPE=\"TEXT\" NAME=\"keyword\" SIZE=\"15\">";
  print "<INPUT TYPE=\"SUBMIT\" VALUE=\"Search\">";
  print "</FORM></TD><TR></TABLE></CENTER></body></html>\n";
  exit;
 }

Program Analysis

(1)Invoke the Perl interpreter.

(2) Specify the database path and name. In our example, we put our database in a file called "students.db". Absolute path name must be specified right here. Here are all the records in the file:

222222222,Yu,Zhanshou,Computer,3.0,(713)748-1980,zyu@bayou.uh.edu
123456789,Smith,Mike,Physics,3.13,(713)112-2345,smith@jetson.uh.edu
234567891,Jordan,Mike,Chemistry,3.45,(281)335-6789,jordan@bayou.uh.edu
178329213,Yu,Jeffrey,Biology,4.00,None,jeff@bayou.uh.edu
193871935,Wu,Cai,Computer,3.78,(409)762-1045,cwu@cs.uh.edu

(3) Get the input string from the form.
(4) Decode and parsing the input string.
(5) Print the HTML header.
(6)Call the &missing_field subrountine to display the Form again if keyword missing.
(7)Open the database file for reading, if failed, print error message:
```
open(DB,"<$DATABASE") || die "Can't open $DATABASE\n";
```
(8)This part is the core of this program. The statement:
```
 $inline=<DB>
```
Get one line each time from file and assign it to varaible $inline. Then remove the last line-feed charater from $inline:
```
 chop(#inline));
```
Now we check whether the keyword is in the current line:
```
if($inline =~ /$value/i) 
```
If there is a match, increment the counter and store this line(record) to an array:
```
   $count++; 
   @matches[$count] = $inline;
```
Loop until to the end of the file.
(9) Print the HTML head title, etc. tag, prepare for output content.

(10)if counter is greater than 0, that's mean we have at least one match. Print out all the record stored in matched array:

foreach $record (@matches)
  {
	($ssn,$last,$first,$major,$gpa,$phone,$email) = split(/,/,$record);
	print "<PRE>\n";
	print "SSN           : $ssn\n";
	print "Last name     : $last\n";
	print "First name    : $first\n";
	print "Major         : $major\n";
	print "GPA           : $gpa\n";
	print "Phone         : $phone\n";
	print "Email         : $email\n";
	print "</PRE><HR>\n";
   }
 }

Note that:

($ssn,$last,$first,$major,$gpa,$phone,$email) = split(/,/,$record);

Split each fields in this record.

(11)If no match in this database, we have to say sorry.
(12) missing_field is a subrountine to display the input form if the keyword is missing.