How to apply case when with if condition in MySql - mysql

Question

I have below mentioned two tables:
Table 1
ID Key
TTT-1 atre-0-1
TTT-2 atrt-4-2
TTT-3 attr-1-3
TTT-4 aert-2-5
Table2
Key Red1 Red2
atre-0-1 10 25
atre-0-1 15 07
atre-0-1 16 19
atrt-4-2 11 21
atrt-4-2 07 22
attr-1-3 -4 3
attr-1-3 33 11
attr-1-3 50 45
aert-2-5 -5 2
aert-2-5 -4 1
By utilizing the above tow tables, I want to fetch the minimum value of Red1 and Red2 group by ID with the below mentioned condition.
For any ID if any Red1 and Red2 value is between -5 to 5 than consider the other values which are maximum of five, If there are only one entry available for a ID against which value is between range -5 to 5 than only consider -5 to 5 value for minimum criteria.
Required Output:
ID Number
TTT-1 07
TTT-2 07
TTT-3 11
TTT-4 -5
I have written below mentioned query, but it didn't work properly.
select t1.ID,
case when min(t2.Red1)<min(t2.Red2) then min(t2.Red1) else min(t2.Red2) End as `Number`
from Table1 t1
left join Table2 t2 on t1.key=t2.key
group by t1.ID;

Answer 1

The following query should solve this problem:
SELECT t1.ID,
CASE WHEN min(t2.Red1)<min(t2.Red2) THEN t2.min_red1 ELSE t2.min_red2 END AS
`Number`
FROM Table1 t1
LEFT JOIN
(
SELECT
key,
Red1
Red2
min(Red1) AS min_red1,
min(Red2) AS min_red2
FROM Table2 ) AS t2
ON t1.key=t2.key
GROUP BY t1.ID;

Answer 2

You can use the below SQL, here is the example as per your expectation.
Query:
SELECT
a.ID,
CASE
WHEN
LEAST(MIN(b.red1), MIN(b.red2)) BETWEEN - 5 AND 5
THEN
IFNULL(LEAST(MIN(CASE
WHEN red1 NOT BETWEEN - 5 AND 5 THEN red1
END),
MIN(CASE
WHEN red2 NOT BETWEEN - 5 AND 5 THEN red2
END)),
LEAST(MIN(b.red1), MIN(b.red2)))
ELSE LEAST(MIN(b.red1), MIN(b.red2))
END AS `Number`
FROM
table1 a
JOIN
table2 b ON a.key = b.key
GROUP BY a.ID;
Example:
mysql> create table table1(ID varchar(20),`key` varchar(20));
Query OK, 0 rows affected (0.23 sec)
mysql> insert into table1 values
-> ('TTT-1','atre-0-1'),
-> ('TTT-2','atrt-4-2'),
-> ('TTT-3','attr-1-3'),
-> ('TTT-4','aert-2-5');
Query OK, 4 rows affected (0.27 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql>
mysql> create table table2(`key` varchar(20),red1 int(5),red2 int(5));
Query OK, 0 rows affected (0.30 sec)
mysql> insert into table2 values
-> ('atre-0-1',10,25),
-> ('atre-0-1',15,07),
-> ('atre-0-1',16,19),
-> ('atrt-4-2',11,21),
-> ('atrt-4-2',07,22),
-> ('attr-1-3',-4,3),
-> ('attr-1-3',33,11),
-> ('attr-1-3',50,45),
-> ('aert-2-5',-5,2),
-> ('aert-2-5',-4,1);
Query OK, 10 rows affected (0.29 sec)
Records: 10 Duplicates: 0 Warnings: 0
mysql>
mysql> select * from table1;
+-------+----------+
| ID | key |
+-------+----------+
| TTT-1 | atre-0-1 |
| TTT-2 | atrt-4-2 |
| TTT-3 | attr-1-3 |
| TTT-4 | aert-2-5 |
+-------+----------+
4 rows in set (0.20 sec)
mysql> select * from table2;
+----------+------+------+
| key | red1 | red2 |
+----------+------+------+
| atre-0-1 | 10 | 25 |
| atre-0-1 | 15 | 7 |
| atre-0-1 | 16 | 19 |
| atrt-4-2 | 11 | 21 |
| atrt-4-2 | 7 | 22 |
| attr-1-3 | -4 | 3 |
| attr-1-3 | 33 | 11 |
| attr-1-3 | 50 | 45 |
| aert-2-5 | -5 | 2 |
| aert-2-5 | -4 | 1 |
+----------+------+------+
10 rows in set (0.21 sec)
mysql>
mysql> SELECT
-> a.ID,
-> CASE
-> WHEN
-> LEAST(MIN(b.red1), MIN(b.red2)) BETWEEN - 5 AND 5
-> THEN
-> IFNULL(LEAST(MIN(CASE
-> WHEN red1 NOT BETWEEN - 5 AND 5 THEN red1
-> END),
-> MIN(CASE
-> WHEN red2 NOT BETWEEN - 5 AND 5 THEN red2
-> END)),
-> LEAST(MIN(b.red1), MIN(b.red2)))
-> ELSE LEAST(MIN(b.red1), MIN(b.red2))
-> END AS `Number`
-> FROM
-> table1 a
-> JOIN
-> table2 b ON a.key = b.key
-> GROUP BY a.ID;
+-------+--------+
| ID | Number |
+-------+--------+
| TTT-1 | 7 |
| TTT-2 | 7 |
| TTT-3 | 11 |
| TTT-4 | -5 |
+-------+--------+
4 rows in set (0.28 sec)