如何将两个 select 查询与不同的列组合起来

Question

I know that union can be done to combine two queries if they have same number and type of columns. But I've a condition where I've to combine two select statement with different tables and different columns though 1 table is common in both ie PatientAppointment . Here are the two statements:

select p.CDRId, p.Gender,p.MRN,p.DoB as DOB,pa.AppointmentDateTime,cn.Description,ehv.ProgramName,
 cn.CreatedBy as CareTeamStaffMember,cn.Profile as Role,cn.Title as Credentials,
 date_format(pa.AppointmentDateTime, '%Y-%m') BillingMonth,
 ((case when duration like '% hour%' then substring_index(duration, ' hour', 1) * 60 else 0 end) +
(case when duration like '%min%' then substring_index(substring_index(duration, ' min', 1), ' ', -1) + 0 else 0 end)) as minutes
from Patient p inner join EnrollmentHistoryView ehv on ehv.CDRId = p.CDRId
inner join ClinicalNote cn on cn.CDRId = p.CDRId
inner join PatientAppointment pa on pa.CDRId = p.CDRId 
where p.CDRId='9493b505-03b9-46a0-b009-99b34f7a5d41' 
and ehv.ProgramName!='N/A'
group by p.CDRId, p.Gender, p.MRN, p.Dob, pa.AppointmentDateTime,cn.Description,cn.CreatedBy,cn.Profile,cn.Title,pa.Duration,ehv.ProgramName

UNION

SELECT AppointmentDateTime,
       duration,
       minutes,
       CASE WHEN @prev_month != BillingMonth
            THEN total >= 20
            WHEN @prev_total < 20 
            THEN 1
            ELSE 0 
            END 99457Elig,
       CASE WHEN @prev_month != BillingMonth
            THEN total >= 40
            WHEN @prev_total < 40
            THEN 1
            ELSE 0 
            END 99458Elig,
       @prev_month := BillingMonth BillingMonth,
       @prev_total := total total
FROM (select AppointmentDateTime,
             duration,
             @cur_dur := ((case when duration like '% hour%' then substring_index(duration, ' hour', 1) * 60 else 0 end) +
                         (case when duration like '%min%' then substring_index(substring_index(duration, ' min', 1), ' ', -1) + 0 else 0 end)) as minutes,

             CASE WHEN @year_month = date_format(AppointmentDateTime, '%Y-%m')
                  THEN @cum_sum := @cum_sum + @cur_dur
                  ELSE @cum_sum := @cur_dur
                  END total,
             @year_month := date_format(AppointmentDateTime, '%Y-%m') BillingMonth

      from PatientAppointment, (SELECT @year_month:='', @cum_sum:=0, @cur_dur:=0) variables
      ORDER BY AppointmentDateTime) subquery,
(SELECT @prev_month:=0, @prev_total:=0) variable
ORDER BY AppointmentDateTime

The query is too complex and I can't create the data set also. Please help me with the approach. Give me some suggestion at least. I'll try it myself.

Answer 1

Consider your first query as Query1 and second query as Query2 , you can use simple join between these two.

As you said PatientAppointment table is common in both, use its primary key( CDRId ) as joining between these two. So your query would look like.

SELECT * 
FROM ( Query1 ) AS table1
INNER JOIN ( Query2) AS table2 ON table1.CDRId = table2.CDRId;