Index: core/kernel/db/cat_event_handler.php
===================================================================
--- core/kernel/db/cat_event_handler.php
+++ core/kernel/db/cat_event_handler.php
@@ -1320,8 +1320,11 @@
 
 			// search by partial word matches too
 			$revelance_parts[] = 'IF('.$field.' LIKE "%'.implode(' ', $positive_words).'%", '.$weight_sum.', 0)';
-			foreach ($positive_words as $keyword) {
-				$revelance_parts[] = 'IF('.$field.' LIKE "%'.$keyword.'%", '.$weight.', 0)';
+
+			if ( count($positive_words) > 1 ) {
+				foreach ( $positive_words as $keyword ) {
+					$revelance_parts[] = 'IF(' . $field . ' LIKE "%' . $keyword . '%", ' . $weight . ', 0)';
+				}
 			}
 		}
 
Index: core/units/categories/categories_event_handler.php
===================================================================
--- core/units/categories/categories_event_handler.php
+++ core/units/categories/categories_event_handler.php
@@ -2663,8 +2663,11 @@
 
 				// search by partial word matches too
 				$revelance_parts[] = 'IF('.$field.' LIKE "%'.implode(' ', $positive_words).'%", '.$weight_sum.', 0)';
-				foreach ($positive_words as $keyword) {
-					$revelance_parts[] = 'IF('.$field.' LIKE "%'.$keyword.'%", '.$weight.', 0)';
+
+				if ( count($positive_words) > 1 ) {
+					foreach ( $positive_words as $keyword ) {
+						$revelance_parts[] = 'IF(' . $field . ' LIKE "%' . $keyword . '%", ' . $weight . ', 0)';
+					}
 				}
 			}