datetime - MySQL - convert timed event rows to ranges of states -



datetime - MySQL - convert timed event rows to ranges of states -

let's house gets painted every often, , track changes (the 'paint' event) in simple table:

_______________________ / paintdate | newcolor \ |-----------|-----------| | 1/2/2012 | reddish | | 3/5/2013 | bluish | | 9/9/2013 | greenish | \___________|___________/

is there select statement can give me table of the date ranges house @ specific color?

desired output:

_______________________________ / | | color \ |----------|----------|---------| | 1/2/2012 | 3/5/2013 | reddish | | 3/5/2013 | 9/9/2013 | bluish | | 9/9/2013 | null | greenish | -- not repainted yet, date in 'to' column should null \__________|__________|_________/

well can utilize query

select p.paintdate `from`, l.paintdate `to`, p.newcolor `color` paint p left bring together (select * paint limit 1, 18446744073709551615) l on l.paintdate = (select paintdate paint paintdate > p.paintdate order paintdate asc limit 1)

output

from | | color ------------------------------- 2012-02-01 | 2012-05-03 | reddish 2012-05-03 | 2013-09-09 | bluish 2013-09-09 | (null) | greenish

demo

the above query can improved this

select p.paintdate `from`, l.paintdate `to`, p.newcolor `color` paint p left bring together paint l on l.paintdate = (select paintdate paint paintdate > p.paintdate order paintdate asc limit 1)

demo

mysql datetime select

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