Merging rows in MySQL with null values on same timestamp

Question

I have a query that is returning all of the data that I want but with a lot of extra null values because of how the case statements execute. I am trying to get rid of all of the null values just have one row of data for each timestamp. Here is the query:

SELECT
    FROM_UNIXTIME(t_stamp/1000, '%b %D, %Y %h:%i %p') as t_stamp,
    (case when t.id = 460 then s.floatvalue end) as ait_3022_btu_dry,
    (case when t.id = 460 then s.dataintegrity end) as ait_3022_btu_dry_qual,
    (case when t.id = 481 then s.floatvalue end) as ait_3022_ch4,
    (case when t.id = 481 then s.dataintegrity end) as ait_3022_ch4_qual,
    (case when t.id = 622 then s.floatvalue end) as fqe_3004_cd_lr,
    (case when t.id = 622 then s.dataintegrity end) as fqe_3004_cd_lr_qual,
    (case when t.id = 641 then s.floatvalue end) as at_3005,
    (case when t.id = 641 then s.dataintegrity end) as at_3005_qual,
    (case when t.id = 647 then s.floatvalue end) as ft_3004_scfm,
    (case when t.id = 647 then s.dataintegrity end) as ft_3004_scfm_qual,
    (case when t.id = 934 then s.floatvalue end) as ft_3005_scfm,
    (case when t.id = 934 then s.dataintegrity end) as ft_3005_scfm_qual
FROM sqlt_data_1_2019_10 s
    inner join sqlth_te t
    on s.tagid = t.id
WHERE
    (s.floatvalue AND s.dataintegrity) IS NOT NULL
    AND 
    (t_stamp >= 1570597200000 and t_stamp <= 1570629600000)
    AND 
    (tagid = 934
    or tagid = 647
    or tagid = 622
    or tagid = 641
    or tagid = 460
    or tagid = 481)
ORDER BY t_stamp ASC

and here is what it is returning:

I need to return just one row per timestamp

Answer 1

You just need to turn on aggregation:

SELECT
    FROM_UNIXTIME(t_stamp/1000, '%b %D, %Y %h:%i %p') as t_stamp,
    MAX(case when t.id = 460 then s.floatvalue end) as ait_3022_btu_dry,
    MAX(case when t.id = 460 then s.dataintegrity end) as ait_3022_btu_dry_qual,
    MAX(case when t.id = 481 then s.floatvalue end) as ait_3022_ch4,
    MAX(case when t.id = 481 then s.dataintegrity end) as ait_3022_ch4_qual,
    MAX(case when t.id = 622 then s.floatvalue end) as fqe_3004_cd_lr,
    MAX(case when t.id = 622 then s.dataintegrity end) as fqe_3004_cd_lr_qual,
    MAX(case when t.id = 641 then s.floatvalue end) as at_3005,
    MAX(case when t.id = 641 then s.dataintegrity end) as at_3005_qual,
    MAX(case when t.id = 647 then s.floatvalue end) as ft_3004_scfm,
    MAX(case when t.id = 647 then s.dataintegrity end) as ft_3004_scfm_qual,
    MAX(case when t.id = 934 then s.floatvalue end) as ft_3005_scfm,
    MAX(case when t.id = 934 then s.dataintegrity end) as ft_3005_scfm_qual
FROM sqlt_data_1_2019_10 s
    inner join sqlth_te t
    on s.tagid = t.id
WHERE
    (s.floatvalue AND s.dataintegrity) IS NOT NULL
    AND 
    (t_stamp >= 1570597200000 and t_stamp <= 1570629600000)
    AND 
    (tagid = 934
    or tagid = 647
    or tagid = 622
    or tagid = 641
    or tagid = 460
    or tagid = 481)
GROUP BY FROM_UNIXTIME(t_stamp/1000, '%b %D, %Y %h:%i %p')
ORDER BY t_stamp ASC

Also as commented by Gordon Linoff, please note that the conditions on tagid in the WHERE clause would be better written:

tag_id IN (934, 647, 622, 641, 460, 481)

EDIT:

Since I brought up the subject, the where clause should look like:

WHERE s.floatvalue IS NOT NULL AND
      s.dataintegrity IS NOT NULL AND
      t_stamp >= 1570597200000 AND
      t_stamp <= 1570629600000 AND
      tagid IN (934, 647, 622, 641, 460, 481)