retrieve row from multiple row of table in oracle - sql

Question

I want to retrieve data from three table
for example
Table_1 : NAME_A
PD_ID
A
B
C
Table_2 : NAME_B Primary_key PD_ID,EV_N
PD_ID EV_N EV_DEC
A 1 one
A 2 Two
B 1 one
B 2 Two
B 3 THREE
C 1 one
C 2 Two
Table_3 : NAME_C Primary key PD_ID
PD_ID, FFT_NAME, FFT_DESC
A XY XY_DESC
B ZY ZY_DESC
B XY XY_DESC
C ZY ZY_DESC
C XY XY_DESC
C PY PY_DESC
Required Output
PD_ID EV_N EV_DEC FFT_NAME FFT_DESC
A 1 ONE XY XY_DESC
A 2 TWO
B 1 ONE ZY ZY_DESC
B 2 TWO XY XY_DESC
B 3 THREE
C 1 ONE ZY ZY_DESC
C 2 Two XY XY_DESC
PY PY_DESC

Answer 1

The idea is to range records in both tables and then use this range numbers in a full outer join:
with
t1 as (
select 'A' pd_id from dual union all
select 'B' pd_id from dual union all
select 'C' pd_id from dual
),
t2 as (
select 'A' pd_id, 1 EV_N, 'one' EV_DEC from dual union all
select 'A' pd_id, 2 EV_N, 'two' EV_DEC from dual union all
select 'B' pd_id, 1 EV_N, 'one' EV_DEC from dual union all
select 'B' pd_id, 2 EV_N, 'two' EV_DEC from dual union all
select 'B' pd_id, 3 EV_N, 'three' EV_DEC from dual union all
select 'C' pd_id, 1 EV_N, 'one' EV_DEC from dual union all
select 'C' pd_id, 2 EV_N, 'two' EV_DEC from dual
),
t3 as (
select 'A' pd_id, 'XY' FFT_NAME, 'XY_DESC' FFT_DESC from dual union all
select 'B' pd_id, 'ZY' FFT_NAME, 'ZY_DESC' FFT_DESC from dual union all
select 'B' pd_id, 'XY' FFT_NAME, 'XY_DESC' FFT_DESC from dual union all
select 'C' pd_id, 'ZY' FFT_NAME, 'ZY_DESC' FFT_DESC from dual union all
select 'C' pd_id, 'XY' FFT_NAME, 'XY_DESC' FFT_DESC from dual union all
select 'C' pd_id, 'PY' FFT_NAME, 'PY_DESC' FFT_DESC from dual
)
select coalesce(t22.pd_id,t33.pd_id) pd_id,
t22.ev_dec,
t33.FFT_NAME,
t33.FFT_DESC
from (
select pd_id, ev_n, ev_dec, row_number() over (partition by pd_id order by ev_n, ev_dec) rn
from t2
) t22
full join (
select pd_id, FFT_NAME, FFT_DESC, row_number() over (partition by pd_id order by FFT_NAME, FFT_DESC) rn
from t3
) t33
on t22.pd_id = t33.pd_id
and t22.rn = t33.rn

Answer 2

This won't produce the exact output you specify but it will produce a consistent and predictable output:
select t1.PD_ID
, t2.EV_N
, t2.EV_DEC
, t2.FFT_NAME
, t2.FFT_DESC
from name_a t1
cross join ( select coalesce(b.p_id, c.p_id) as p_id
, b.ev_n
, upper(b.ev_dec) as ev_dec
, c.fft_name
, c.fft_desc
from ( select * from name_b ) b
full outer join
( select c.*
, row_number() over (partition by c.p_id
order by c.fft_name) as rn
from name_c c) c
on c.p_id = b._pid
and c.rn = b.ev_n) t2
where t1.p_id = t2.p_id
order by t1.p_id
, t2.ev_n nulls last