Simple incremental counter in mysql query - mysql

Question

My Query:
SET #rank = 0;
SELECT Jobs.ID, Jobs.StatusID, (#rank:=#rank+1) AS Rank
FROM Jobs
INNER JOIN JobStatuses ON Jobs.StatusID = JSID
INNER JOIN JobStatusGroups ON Jobs.SGrID = JSGID
WHERE Jobs.StatusID = 3
ORDER BY JobTitle DESC
LIMIT 5
Results in:
1010 3 1
1011 3 2
1013 3 4
1014 3 5
1016 3 7
Should result in:
1010 3 1
1011 3 2
1013 3 3
1014 3 4
1016 3 5
How can I make #rank only increment if row is actually being inserted? I tried cross join did not work. I also tried the following:
SELECT Jobs.ID, Jobs.StatusID, (#rank:=#rank+1) AS Rank
FROM Jobs, (SELECT #rank := 0) tempRank
INNER JOIN JobStatuses ON Jobs.StatusID = JSID
INNER JOIN JobStatusGroups ON Jobs.SGrID = JSGID
WHERE Jobs.StatusID = 3
ORDER BY JobTitle DESC
LIMIT 5
But gives me an error saying Jobs.StatusID does not exist.

Answer 1

instead of setting it outside cross join it in the select (i prefer cross join just so its easier to read aka i know where im creating the variable) that way the count wont be messed up
INSERT IGNORE INTO MyTable(MyID, UserID, JobID, StatusID, SortOrder)
SELECT :myid, :userid, Jobs.ID, Jobs.StatusID, (#rank:=#rank+1) AS Rank
FROM Jobs
INNER JOIN JobStatuses ON Jobs.StatusID = JSID
CROSS JOIN (SELECT #rank := 0) temp
LEFT JOIN JobStatusGroups ON Jobs.SGrID = JSGID
WHERE ...
ORDER BY JobTitle DESC
on terms of performance I haven't ever noticed performance issues with using the variables instantiation inside a join on the table
one thing you can try is maybe the ORDER BY is messing up the order / count so you can try encapsulating it in a subselect
SELECT ID, StatusID, (#rank:=#rank+1) AS Rank
FROM
( SELECT Jobs.ID, Jobs.StatusID
FROM Jobs
INNER JOIN JobStatuses ON Jobs.StatusID = JSID
INNER JOIN JobStatusGroups ON Jobs.SGrID = JSGID
WHERE Jobs.StatusID = 3
ORDER BY JobTitle DESC
LIMIT 5
)t
CROSS JOIN (SELECT #rank := 0) temp

Answer 2

Try This updated one:
SET #rank = 0;
INSERT INTO MyTable(MyID, UserID, JobID, StatusID, SortOrder)
SELECT myid, userid, Jobs.ID, Jobs.StatusID, (#rank:=#rank+1) AS Rank
FROM Jobs
INNER JOIN JobStatuses ON Jobs.StatusID = JobStatuses.JSID
LEFT JOIN JobStatusGroups ON Jobs.SGrID = JobStatusGroups.JSGID
ON DUPLICATE KEY update MyID=IF((#rank:=#rank-1) <> NULL IS NULL, VALUES(MyID), NULL);