insertintoarticle(id,class,title,content)selectid,'2',title,contentfromarticlewhereclass='1'

如果id为自动编号,就把改为:

insertintoarticle(class,title,content)select'2',title,contentfromarticlewhereclass='1'

如果class为数字类型,则去掉单引号.