Get result from joined tables - mysql

Question

I have 2 tables:
Table 1:
| jobid | jobname |
| 1 | job a |
| 2 | job b |
Table 2:
| id | jobid | statusid | statusdate | desc |
| 1 | 1 | 100 | 2019.04.25 10:00:00 | first |
| 2 | 2 | 100 | 2019.04.25 11:00:00 | first |
| 3 | 2 | 100 | 2019.04.25 12:00:00 | second |
Jobs in table2 can have more then one same "statusid", but different "statusdate" and "desc"
I need to get jobs list with the last "statusid" = 100 like this :
| 1 | job a | 1 | 1 | 100 | 2019.04.25 10:00:00 | first |
| 2 | job b | 3 | 2 | 100 | 2019.04.25 12:00:00 | second |
SELECT * FROM table1
INNER JOIN table2 ON table1.id = table2.jobid
GROUP BY table1.id
This query return wrong result like:
| 1 | job a | 1 | 1 | | 100 | 2019.04.25 10:00:00 | first |
| 2 | job b | 3 | 2 | 2 | 100 | 2019.04.25 11:00:00 | first |

Answer 1

You should be able to accomplish that by doing something like this:
Table
drop table if exists table1;
create table table1 (jobid int, jobname char(10));
insert into table1 values (1, 'job a'), (2, 'job b');
drop table if exists table2;
create table table2 (
id int,
jobid int,
statusid int,
statusdate timestamp,
`desc` char(10)
);
insert into table2 values
(1,1,100,'2019.04.25 10:00:00','first')
,(2,2,100,'2019.04.25 11:00:00','first')
,(3,2,100,'2019.04.25 12:00:00','second');
Query
select
t1.*,
t2.*
from table1 t1
inner join (
select jobid, max(statusdate) as maxstatusdate
from table2
group by jobid
) tn on t1.jobid = tn.jobid
inner join table2 t2 on tn.jobid = t2.jobid and tn.maxstatusdate = t2.statusdate;
Results
jobid jobname id jobid statusid statusdate desc
1 job a 1 1 100 25.04.2019 10:00:00 first
2 job b 3 2 100 25.04.2019 12:00:00 second
Explanation
For each job ID, find the maximum status date
Join that to table1 to get information from table1. Common field is jobid
Join their result to table2 that has all the remaining information you want. Common fields are jobid and statusdate. Since we aliased max status date to a different name, make sure we are using the correct name in the join
Example: https://rextester.com/HRSWZ89705

Answer 2

DROP TABLE IF EXISTS table1;
CREATE TABLE table1
(jobid INT NOT NULL PRIMARY KEY
,jobname VARCHAR(12) UNIQUE
);
INSERT INTO table1 VALUES
(1,'job a'),
(2,'job b'),
(3,'job c');
DROP TABLE IF EXISTS table2;
CREATE TABLE table2
(id SERIAL PRIMARY KEY
,jobid INT NOT NULL
,statusid INT NOT NULL
,statusdate DATETIME NOT NULL
,description VARCHAR(12) NOT NULL
);
INSERT INTO table2 VALUES
(1,1,100,'2019-04-25 10:00:00','first'),
(2,2,100,'2019-04-25 11:00:00','first'),
(3,2,100,'2019-04-25 12:00:00','second');
SELECT a.*
, b.id x_id
, b.statusid
, b.statusdate
, b.description
FROM table1 a
LEFT
JOIN
( SELECT x.*
FROM table2 x
JOIN
( SELECT MAX(id) id
FROM table2
WHERE statusid = 100
GROUP
BY jobid
) y
ON y.id = x.id
) b
ON b.jobid = a.jobid
;
+-------+---------+------+----------+---------------------+-------------+
| jobid | jobname | x_id | statusid | statusdate | description |
+-------+---------+------+----------+---------------------+-------------+
| 1 | job a | 1 | 100 | 2019-04-25 10:00:00 | first |
| 2 | job b | 3 | 100 | 2019-04-25 12:00:00 | second |
| 3 | job c | NULL | NULL | NULL | NULL |
+-------+---------+------+----------+---------------------+-------------+

Answer 3

SELECT
t1.*,t2.* FROM
(SELECT
MAX(id) as id
FROM
table2
WHERE statusid = 100
GROUP BY jobid) AS f
JOIN table2 t2
ON t2.id = f.id
JOIN table1 t1
ON t2.jobid = t1.jobid
The sub query select finds the last id for a row with statusid 100, then it joins the actual table based on this id.
You can reorder this as you wish using the correct joins.