Question

assuming i have the following rows :

'employee' , 'is_here' , 'ts'
      1    ,    1      ,   22
      2    ,    1      ,   33
      1    ,    0      ,   44
      1    ,    0      ,   55
      2    ,    0      ,   66
      1    ,    0      ,   77
      2    ,    0      ,   88
      1    ,    1      ,   99

is there any way to display the results of some employee when then is_here changes ?

for example i want to get the rows where employee #1 is_here changed , so the output will be :

1,1,22
1,0,44
1,1,99

That would be challenging i guess 🙂

Answer 1

As long as you run the query for only one employee at the time

set @state = -1;

select employee,
       @state := is_here as changed_to,
       ts
  from working
 where employee = 1 
   and (@state = -1 or @state != is_here);

http://sqlfiddle.com/#!2/a71d8/11