H2 SQL数据库-如果记录不存在，则插入

以下内容适用于MySQL，PostgreSQL和H2数据库：

drop table ACCESSLEVELS;create table ACCESSLEVELS(id int, name varchar(255));insert into ACCESSLEVELS select * from (select 0, 'admin' unionselect 1, 'SEO' unionselect 2, 'sales director' unionselect 3, 'manager' unionselect 4, 'REP') x where not exists(select * from ACCESSLEVELS);