SearchWordsSQL

Converts a Google-style query expression of seach words into an SQL boolean expression and a MySQL IBL (a.k.a. 'Implied Boolean Logic' or 'IN BOOLEAN MODE') one for full-text search.

Quickstart

To begin with, put SearchWordsSQL.php on the PHP library path.

If the database server supports an SQL LIKE operator for text search, your code would be like:

require_once 'SearchWordsSQL.php';
$searchwords = "php library OR code";

$sqlbuilder = new SearchWordsSQL\SQLBuilder("BodyText LIKE ?", "\SearchWordsSQL\SQLLikeValueCallback");
    // The first argument is a parameterized SQL boolean expression for each word
    // The second specifies the values should be converted for a LIKE operator.
$result = $sqlbuilder->Build($searchwords);
echo $result['SQL'] . "\n";
    // produces '((BodyText LIKE ?) AND ( (BodyText LIKE ?) OR (BodyText LIKE ?) ) )'
echo join(", ", $result['value']) . "\n";
    // produces '%php%, %library%, %code%'
    
$db = new PDO("pgsql:host=localhost");
$stmt = $db->prepare("SELECT * FROM BookText WHERE ${result['SQL']}");
$stmt->execute($result['value']);
	// execute it with the returned values as the parameters

If you would like to utilize MySQL IBL:

require_once 'SearchWordsSQL.php';
$searchwords = "php library OR code";

$sqlbuilder = new SearchWordsSQL\SQLBuilder("");
	// We don't want an SQL expression
$result = $sqlbuilder->Build($searchwords);
echo $result['IBL'] . "\n";
	// produces '+php (library code)'
    
$db = new PDO("mysql:host=localhost");
$stmt = $db->prepare("SELECT * FROM BookText WHERE MATCH (BodyText) AGAINST (? IN BOOLEAN MODE)");
$stmt->execute(array($result['IBL']));

Syntax supported for search words

• Words separated by space(s) means all of them should be included in the text to be searched in.
• Words separated by OR in upper case means at least one of them should be included.
• A pair of parenthesis () groups expression inside.
• a b OR c d means a (b OR c) d.
• A word following minus sign - means it must not be included.
• A pair of double quotation marks "" specifies words inside containing spaces to be treated as a word. You can escape with a backslash.
• * inside a word means 'any characters.' Bare star(s) are not allowed.

API Documentation

Run makedoc.sh and see ./doc/index.html. Also there are online documents.

License

LGPLv2 or later. See COPYING.LESSER.

Caveats

• This library does not comform to naming convention of standard PHP codes.
• IBL expression the library produces might be too complex for MySQL to interpret.

Changelog

v0.2.1

• Changed the license from LGPLv3 to LGPLv2.1 or later.

v0.2

• Added support for prefix functions.

v0.1

• Initial Release.