Support for FOR UPDATE and LOCK IN SHARE MODE in selects

MysqliDb.php

@@ -139,6 +139,19 @@ class MysqliDb
      */
     protected $_nestJoin = false;
     private $_tableName = '';
+
+    /**
+     * FOR UPDATE flag
+     * @var boolean
+     */
+    protected $_forUpdate = false;
+
+    /**
+     * LOCK IN SHARE MODE flag
+     * @var boolean
+     */
+    protected $_lockInShareMode = false;
+
     /**
      * Variables for query execution tracing
      *
@@ -247,6 +260,8 @@ class MysqliDb
         $this->_queryOptions = array();
         $this->returnType = 'Array';
         $this->_nestJoin = false;
+        $this->_forUpdate = false;
+        $this->_lockInShareMode = false;
         $this->_tableName = '';
         $this->_lastInsertId = null;
         $this->_updateColumns = null;
@@ -401,7 +416,7 @@ class MysqliDb
     public function setQueryOption ($options) {
         $allowedOptions = Array ('ALL','DISTINCT','DISTINCTROW','HIGH_PRIORITY','STRAIGHT_JOIN','SQL_SMALL_RESULT',
                           'SQL_BIG_RESULT','SQL_BUFFER_RESULT','SQL_CACHE','SQL_NO_CACHE', 'SQL_CALC_FOUND_ROWS',
-                          'LOW_PRIORITY','IGNORE','QUICK', 'MYSQLI_NESTJOIN');
+                          'LOW_PRIORITY','IGNORE','QUICK', 'MYSQLI_NESTJOIN', 'FOR UPDATE', 'LOCK IN SHARE MODE');
         if (!is_array ($options))
             $options = Array ($options);
 
@@ -412,6 +427,10 @@ class MysqliDb
 
             if ($option == 'MYSQLI_NESTJOIN')
                 $this->_nestJoin = true;
+            else if ($option == 'MYSQLI_FOR_UPDATE')
+                $this->_forUpdate = true;
+            else if ($option == 'MYSQLI_LOCK_IN_SHARE_MODE')
+                $this->_lockInShareMode = true;
             else
                 $this->_queryOptions[] = $option;
         }
@@ -884,6 +903,10 @@ class MysqliDb
         $this->_buildOrderBy();
         $this->_buildLimit ($numRows);
         $this->_buildOnDuplicate($tableData);
+        if ($this->_forUpdate)
+            $this->_query .= ' FOR UPDATE';
+        if ($this->_lockInShareMode)
+            $this->_query .= ' LOCK IN SHARE MODE';
 
         $this->_lastQuery = $this->replacePlaceHolders ($this->_query, $this->_bindParams);
 

readme.md

@@ -351,23 +351,25 @@ echo "Showing {$count} from {$db->totalCount}";
 ```
 
 ### Query Keywords
-To add LOW PRIORITY | DELAYED | HIGH PRIORITY | IGNORE and the rest of the mysql keywords to INSERT (), REPLACE (), GET (), UPDATE (), DELETE() method:
+To add LOW PRIORITY | DELAYED | HIGH PRIORITY | IGNORE and the rest of the mysql keywords to INSERT (), REPLACE (), GET (), UPDATE (), DELETE() method or FOR UPDATE | LOCK IN SHARE MODE into SELECT ():
 ```php
-$db->setQueryOption('LOW_PRIORITY');
-$db->insert ($table, $param);
+$db->setQueryOption ('LOW_PRIORITY')->insert ($table, $param);
 // GIVES: INSERT LOW_PRIORITY INTO table ...
 ```
+```php
+$db->setQueryOption ('FOR UPDATE')->get ('users');
+// GIVES: SELECT * FROM USERS FOR UPDATE;
+```
 
 Also you can use an array of keywords:
 ```php
-$db->setQueryOption(Array('LOW_PRIORITY', 'IGNORE'));
-$db->insert ($table,$param);
+$db->setQueryOption (Array('LOW_PRIORITY', 'IGNORE'))->insert ($table,$param);
 // GIVES: INSERT LOW_PRIORITY IGNORE INTO table ...
 ```
 
 Same way keywords could be used in SELECT queries as well:
 ```php
-$db->setQueryOption('SQL_NO_CACHE');
+$db->setQueryOption ('SQL_NO_CACHE');
 $db->get("users");
 // GIVES: SELECT SQL_NO_CACHE * FROM USERS;
 ```