framework/db/Migration.php
public function dropIndex($name, $table)
    {
        $time = $this->beginCommand("drop index $name on $table");
        $this->db->createCommand()->dropIndex($name, $table)->execute();
        $this->endCommand($time);
    }
public function dropIndex($name, $table)
    {
        $time = $this->beginCommand("drop index $name on $table");
        $this->db->createCommand()->dropIndex($name, $table)->execute();
        $this->endCommand($time);
    }
Builds and executes a SQL statement for dropping an index.
@param string $name the name of the index to be dropped. The name will be properly quoted by the method.
@param string $table the table whose index is to be dropped. The name will be properly quoted by the method.