what=computer 

   &searchby=location 

   &where=malahide 

   &yourarea=01 

   &radius=thisarea 

   &sortby=default 

Fig. 2: Detail of a typical query string and the corresponding form values 

Each  of  the  variables  correspond  to  an  element  of  the  form  above,  and  the  two  most 

logically important ones are $what and $searchby.  

   $what must be set: its value is what will be compared against a list of categories and a 

list of business names. Any businesses whose names or categories, which contain, in 

this case, the string  computer , will be included in the results table. 

   $searchby is derived from the pair of radio buttons in the form; it will always be set to 

either  location  or  areacode  and this is what decides how the SQL query is to be 

generated.  A  number  of  functions  are  defined  in  dbq.inc:  makareaquery(), 

makecatareaquery(), makewherequery() and makecatwherequery().  

   If  $searchby  ==   location ,  we  are  then  only  concerned  with  the  variables  $what, 

$where and $sortby and we call makewherequery(). 

   If  $searchby  ==   areacode ,  we  are  only  concerned  with  the  variables  $what, 

$yourarea, $radius and $sortby and we call makeareaquery(). 

   Finally, if the $cat variable is set (this will only happen after a user has clicked on a 

category  in  the   Related  categories   panel),  there  exist  two  further  functions, 

makewherequery()  and  makecatwherequery(),  to  additionally  filter  out  only  those 

businesses with the matching category id in the clients table of the database. 

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