--帮你整理了下代码  试试
select  k.patient_id ,
        k.visit_id ,
        k.treat_result ,
        l.patient_id ,
        l.visit_id ,
        l.dept_discharge_from ,
        l.inp_no ,
        l.doctor_in_charge ,
        l.attending_doctor ,
        m.patient_id ,
        m.visit_id ,
        n.dept_code ,
        n.patient_id ,
        n.visit_id ,
        o.dept_code
from    ( select distinct
                    c.*
          from      ( select    b.patient_id ,
                                b.visit_id ,
                                b.TREAT_RESULT
                      from      diagnosis a
                                inner join diagnosis b on ( a.patient_id = b.patient_id
                                                            and a.visit_id = b.visit_id
                                                          )
                      where     a.TREAT_RESULT = '死亡'
                    ) c
        ) k
        left join pat_visit l on ( k.patient_id = l.patient_id
                                   and k.visit_d = l.visit_id
                                 )
        left join pat_master_index m on ( k.patient_id = m.patient_id
                                          and k.visit_id = m.visit_id
                                        )
        left join mr_on_line n on ( k.patient_id = n.patient_id
                                    and k.visit_d = n.visit_id
                                  )

------解决方案--------------------
少加了几个逗号


SQL code
SELECT  k.patient_id, k.visit_id, k.treat_result, l.patient_id, l.visit_id, l.dept_discharge_from, l.inp_no, l.doctor_in_charge, l.attending_doctor,
        m.patient_id, m.visit_id, n.dept_code, n.patient_id, n.visit_id, o.dept_code
FROM    (
          SELECT DISTINCT
                  c.*
          FROM    (
                    SELECT  b.patient_id ,
                            b.visit_id ,
                            b.TREAT_RESULT
                    FROM    diagnosis a
                    JOIN    diagnosis b
                    ON      (
                              a.patient_id = b.patient_id
                              AND a.visit_id = b.visit_id
                            )
                    WHERE   a.TREAT_RESULT = '死亡'
                  ) c
        ) k
LEFT JOIN pat_visit l
ON      (
          k.patient_id = l.patient_id
          AND k.visit_d = l.visit_id
        )
LEFT JOIN pat_master_index m
ON      (
          k.patient_id = m.patient_id
          AND k.visit_id = m.visit_id
        )
LEFT JOIN mr_on_line n
ON      (
          k.patient_id = n.patient_id
          AND k.visit_d = n.visit_id
        )

------解决方案--------------------
看到都脑袋痛

------解决方案--------------------
别名表 k可改改，不需要再嵌套
SQL code
select
    k.patient_id,k.visit_id,k.treat_result,
    l.patient_id,l.visit_id,l.dept_discharge_from,l.inp_no,l.doctor_in_charge,l.attending_doctor,
    m.patient_id,m.visit_id,
    n.dept_code,n.patient_id,n.visit_id,
    o.dept_code
from
(select DISTIN