执行SQL发生错误！错误：no such column: b.type，语句：SELECT a.id,a.pcode,a.scode,a.name,a.filename,a.outlink,b.type,b.urlname FROM ay_content_sort a LEFT JOIN ay_model b ON a.mcode=b.mcode WHERE(a.status=1) AND(a.acode='cn') ORDER BY a.pcode,a.sorting,a.id