diff --git a/framework/yii/db/QueryBuilder.php b/framework/yii/db/QueryBuilder.php
index f65ee25..e8f4aa3 100644
--- a/framework/yii/db/QueryBuilder.php
+++ b/framework/yii/db/QueryBuilder.php
@@ -288,15 +288,16 @@ class QueryBuilder extends \yii\base\Object
 	}	
 	
 	/**
-	 * Builds a SQL statement for removing a constraint to an existing table.
-	 * @param string $name the name of the constraint to be removed.
-	 * @param string $table the table that constraint will be removed from.
-	 * @return string the SQL statement for removing constraint from an existing table.
+	 * Builds a SQL statement for removing a primary key constraint to an existing table.
+	 * @param string $name the name of the primary key constraint to be removed.
+	 * @param string $table the table that the primary key constraint will be removed from.
+	 * @return string the SQL statement for removing a primary key constraint from an existing table.	 *
 	 */
-	public function dropConstraint($name,$table)
+	public function dropPrimarykey($name,$table)
 	{
-		return 'ALTER TABLE ' . $this->quoteTableName($table) . ' DROP CONSTRAINT '
-			. $this->quoteColumnName($name);
+		return 'ALTER TABLE ' . $this->db->quoteTableName($table)
+			. ' DROP CONSTRAINT ' . $this->db->quoteColumnName($name);
+		
 	}	
 
 	/**