<?php
/******************************************************************************
Class Query
*******************************************************************************
Purpose:
To add a logical query to the SearchEngine class. The logic can
be
one of the following : AND , OR, NOT.
Usage:
aquery = new Query("NOT", array("apple", "pear", "bannana"));
*****************************************************************************/
class Query {
//PRIVATE:
var $m_words;
var $m_logic;
//PUBLIC
//
// Constructor
// logic: <AND | OR | NOT>
// words: words to be searched for given logic
function Query($logic, $words) {
$this->m_words = $words;
$this->m_logic = $logic;
}
// print attributes of query
function p() {
echo "$this->m_logic";
reset($this->m_words);
while(list($i, $word) = each($this->m_words))
echo ":$word";
}
};
/******************************************************************************
Class QueryGenerator
*******************************************************************************
purpose:
Generates selection query strings
usage:
query1 = new Query("AND", array("rabbit", "horse", "cow"));
query2 = new Query("OR", array("dogs", "cats", "kangaroos"));
query3 = new Query("NOT", array("sheep"));
querygen = new QueryGenerator(array(query1, query2, query3));
query = querygen->GetQueryString
("animal_table", "mamals_field", "ID_field");
resultid = mysql_query(query);
while(row = mysql_fetch_row(resultid))
echo "got row id ",row["ID_field"],"<br>";
*******************************************************************************/
class QueryGenerator {
var $m_Querys;
var $m_start;
var $m_offset;
var $m_wordmatch;
var $m_casematch;
//PUBLIC:
// querys : array of Query objects
// wordmatch: only match whole words
function QueryGenerator($Querys, $wordmatch=false) {
$this->m_Querys = $Querys;
$this->m_wordmatch = $wordmatch;
$this->m_casematch = $casematch;
$this->Restrict(0,0);
}
// start : start searching data at this pos
// offset : number of records to search after pos
function Restrict($start, $offset) {
$this->m_start = $start;
$this->m_offset = $offset;
}
// table : database table name
// searchfield: field(s) to search in for resultfield(s)
// resultfield: field(s) retrieved from search match
// NOTE: field must be separated by "," eg, "field1,field2"
// RETURN: function returns resultfield
function GetQueryString($table, $searchfield, $resultfield="ID") {
// get the query string
$query_string = $this->BuildQueryString($table, $searchfield,
$resultfield);
// append limit
if ($this->m_start || $this->m_offset) {
$query_string .= "LIMIT $this->m_start";
if($this->m_offset)
$query_string .= ",$this->m_offset";
}
// exec query
return $query_string;
}
//PRIVATE:
// build where clause
function BuildWhereClause($searchfield, $query, $wordmatch) {
$query_string.="(";
while($word = current($query->m_words)) {
if ($wordmatch)
$search_type = "REGEXP '(^|[^a-zA-Z])$word($|
[^a-zA-Z])'";
else
$search_type = "LIKE '%$word%'";
if ($query->m_logic == "NOT")
$query_string.="$searchfield NOT ";
else
$query_string.="$searchfield ";
$query_string.= $search_type;
if (next($query->m_words))
$query_string.=" OR ";
}
$query_string.=")";
return $query_string;
}
// main function that generates the entire query
function BuildQueryString($table, $searchfield, $resultfield) {
// begin query string
$query_string = "SELECT $resultfield FROM $table WHERE ";
// parse searchfields
$searchfields = explode(",", $searchfield);
if(!is_array($searchfields))
$searchfields=array($searchfield);
// build query for each searchfield
while ($searchfield = current($searchfields)) {
$firstquery = true;
$query_string .= "(";
// build current query
reset($this->m_Querys);
while($query = current($this->m_Querys)) {
// append logic
if ($firstquery)
$firstquery=false;
else if ($query->m_logic == "NOT")
$query_string.="AND";
else
$query_string.=$query->m_logic;
// append where clause
$query_string .=
$this->BuildWhereClause($searchfield, $query,
$this->m_wordmatch);
next($this->m_Querys);
}
$query_string .=")";
if (next($searchfields))
$query_string .= "OR";
}
return $query_string;
}
};
?>
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