Mybatis 插入操作时获取主键 （Oracle 触发器与SEQ）

1.通过Oracle序列

-- Create sequence
create sequence SEQ_DW_EWSYSTEM
minvalue 1
maxvalue 999999999999999999999999999
start with 1
increment by 1
cache 20;

<insert id="insertEwsystem" parameterType="Ewsystem">
    <selectKey keyProperty="id" resultType="long" order="BEFORE">
        SELECT SEQ_EWSYSTEM.NEXTVAL FROM DUAL <!-- SELECT DECODE(MAX(ID),NULL,0,MAX(ID))+1 FROM EWSYSTEM -->
    </selectKey>
    INSERT INTO EWSYSTEM (ID,ORG_ID,NAME)VALUES(#{id},#{orgId,jdbcType=VARCHAR},#{name,jdbcType=VARCHAR})
</insert>

2.通过Oracle触发器

create or replace trigger TRG_DW_EWSYSTEM
 before insert
on DW_EWSYSTEM  for each row
begin
select SEQ_DW_EWSYSTEM.nextval into :new.id from dual;
end;