mysq 连表更新

update  table1 a   left join table2 b on a.id = b.user_id left join  table3 c on a.id = c.user_idset a.phone_tel     =  null,    b.id_code       = null,    c.identity_no   = null,    c.identity_type = nullwhere a.phone_tel = '16718787005';