code: public function renameColumn($table, $oldName, $newName)
      {
          return 'ALTER TABLE ' . $this->db->quoteTableName($table)
              . ' RENAME COLUMN ' . $this->db->quoteColumnName($oldName)
              . ' TO ' . $this->db->quoteColumnName($newName);
      }
docs: Builds a SQL statement for renaming a column.
  @param string $table the table whose column is to be renamed. The name will be properly quoted by the method.
  @param string $oldName the old name of the column. The name will be properly quoted by the method.
  @param string $newName the new name of the column. The name will be properly quoted by the method.
  @return string the SQL statement for renaming a DB column.