Code Examples -> Designed to help those implementing a MySQL search engine. Generates select query strings, given logical querys.I made a search engine class that extends this one mail me if intrested.Needs a few changes ( well its only version 1.0 ;)

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PHP Code Examples

Title :	Designed to help those implementing a MySQL search engine. Generates select query strings, given logical querys.I made a search engine class that extends this one mail me if intrested.Needs a few changes ( well its only version 1.0 ;)
Categories :	PHP Classes, MySQL, Search, Regexps	Ed Williams
Date :	Apr 30th 1999
Grade :	2 of 5 (graded 7 times)
Viewed :	20341
File :	No file for this code example.
Images :	No Images for this code example.

Search :	More code by Ed Williams
Action :	Grade This Code Example
Tools :	My Examples List

Code

<?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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User Comments

Krzysztof Wysocki wrote :224
Very nice example of using objects. I wish more stuff were written like that. Congratulations