mybatis mapper insert 设置了selectkey 插入的时候为什么提示ID为null或者没有String类型的setIg
<insert id="insertClasses" parameterType="classes">
<selectKey resultType="java.lang.Long" keyProperty="id" order="BEFORE" >
select seq_classes_id.nextval from dual
</selectKey>
insert into CLASSES(c_name) values(#{name})
</insert>
-----java------
1)session.insert("classes.insertClasses","儿年级英语" ); 提示 No setter found for the keyProperty 'id' in java.lang.String.
2) Classes c = new Classes();
c.setName("儿年级英语");
session.insert("classes.insertClasses",c );
提示:ORA-01400: 无法将 NULL 插入 ("LSPTEST"."CLASSES"."ID")