JOIN from tables evaluating results from one of them - mysql

Question

I have three tables to join, one of them with one-to several values.
SQLFIDDLE
CREATE TABLE Table1 (`id` int, `name` varchar(3));
INSERT INTO Table1 (`id`, `name`)
VALUES (1, 'A'), (2, 'B'), (3, 'C');
CREATE TABLE Table2 (`id` int, `status` int, `date` varchar(9));
INSERT INTO Table2 (`id`, `status`, `date`)
VALUES (1, 1, '''.11..'''), (1, 2, '''.12..'''), (1, 3, '''.13..'''),
(2, 3, '''.23..'''), (3, 1, '''.31..'''), (3, 3, '''.33..''')
;
CREATE TABLE Table3 (`id` int, `value` int);
INSERT INTO Table3 (`id`, `value`)
VALUES (1, 34), (2, 22), (3, 17);
Query 1:
select * from table1
| id | name |
|----|------|
| 1 | A |
| 2 | B |
| 3 | C |
Query 2:
select * from table2;
| id | status | date |
|----|--------|---------|
| 1 | 1 | '.11..' |
| 1 | 2 | '.12..' |
| 1 | 3 | '.13..' |
| 2 | 3 | '.23..' |
| 3 | 1 | '.31..' |
| 3 | 3 | '.33..' |
Query 3:
select * from table3
| id | value |
|----|-------|
| 1 | 34 |
| 2 | 22 |
| 3 | 17 |
I need query that returns for each id:
TABLE1.name, TABLE2.status, TABLE2.date, TABLE3.value
with this condition:
If TABLE2.status =1 exists then return ONLY that line of TABLE2
Else if TABLE2.status =1 does not exists then look for status =2 and return ONLY that line of TABLE2
If no one of those values are present in TABLE2 then skip that id from results
EDIT: TABLE2 has an UNIQUE key for id,status so there can be only one id=1 status=1
Thanks for your help!

Answer 1

Something like this maybe:
select table1.id, table1.name,
coalesce(table2_status1.status, table2_status2.status) as status,
coalesce(table2_status1.date, table2_status2.date) as date,
table3.value
from table1
left join table2 table2_status1 on table2_status1.id = table1.id and table2_status1.status = 1
left join table2 table2_status2 on table2_status2.id = table1.id and table2_status2.status = 2
join table3 on table3.id = table1.id
where (table2_status1.id is not null or table2_status2.id is not null);

Answer 2

Not performant, using subselects, works ( but rlanvins https://stackoverflow.com/a/48235077/7505395 is nicer) :
A,B,C instead of First, Second, ...
select
TABLE1.name,
case
when exists( select 1 from table2 where id = table1.id and status = 1)
then 1
when exists( select 1 from table2 where id = table1.id and status = 2)
then 2
end as T2status,
case
when exists( select 1 from table2 where id = table1.id and status = 1)
then ( select date from table2 where id = table1.id and status = 1)
when exists( select 1 from table2 where id = table1.id and status = 2)
then ( select date from table2 where id = table1.id and status = 2)
end as T2date,
TABLE3.value
from table1
join table3 on table1.id = table3.id
where
exists( select 1 from table2 where id = table1.id and status = 1)
or exists( select 1 from table2 where id = table1.id and status = 2)
Output
Name T2status T2date value
A 1 '.11..' 34
C 1 '.31..' 17
DDL
CREATE TABLE Table1 (`id` int, `name` varchar(3));
INSERT INTO Table1 (`id`, `name`)
VALUES (1, 'A'), (2, 'B'), (3, 'C');
CREATE TABLE Table2 (`id` int, `status` int, `date` varchar(9));
INSERT INTO Table2 (`id`, `status`, `date`)
VALUES (1, 1, '''.11..'''), (1, 2, '''.12..'''), (1, 3, '''.13..'''),
(2, 3, '''.23..'''), (3, 1, '''.31..'''), (3, 3, '''.33..''')
;
CREATE TABLE Table3 (`id` int, `value` int);
INSERT INTO Table3 (`id`, `value`)
VALUES (1, 34), (2, 22), (3, 17);