语句如下：

    1. create_database_stmt:
    2.     CREATE DATABASE [IF NOT EXISTS] database_name
    3.     [database_option_list]
    5. alter_database_stmt:
    6.     ALTER DATABASE database_name
    7.     database_option_list;
    9. drop_database_stmt:
    10.     DROP DATABASE [IF EXISTS] database_name;
    12. database_option_list:
    13.     database_option [database_option ...]
    15. database_option:
    16.       default_charset
    17.     | default_collate
    18.     | primary_zone
    19.     | replica_num
    20.     | {READ ONLY|READ WRITE}
    21.     | default_tablegroup