framework/db/cubrid/QueryBuilder.php
public function dropIndex($name, $table)
    {
        /** @var Schema $schema */
        $schema = $this->db->getSchema();
        foreach ($schema->getTableUniques($table) as $unique) {
            if ($unique->name === $name) {
                return $this->dropUnique($name, $table);
            }
        }

        return 'DROP INDEX ' . $this->db->quoteTableName($name) . ' ON ' . $this->db->quoteTableName($table);
    }
public function dropIndex($name, $table)
    {
        /** @var Schema $schema */
        $schema = $this->db->getSchema();
        foreach ($schema->getTableUniques($table) as $unique) {
            if ($unique->name === $name) {
                return $this->dropUnique($name, $table);
            }
        }

        return 'DROP INDEX ' . $this->db->quoteTableName($name) . ' ON ' . $this->db->quoteTableName($table);
    }
{@inheritdoc}
@see http://www.cubrid.org/manual/93/en/sql/schema/table.html#drop-index-clause