Question

Assume I have the following table:

data_point (creation_datetime DATETIME PRIMARY KEY, 
            data_point INTEGER);

I am looking for an SQL query that would not only tell me if the most recent entry has a data_point value of X, but how many consecutive rows after it also have X as a value.

For instance, assuming the following data:

creation_datetime       data_point
2012-10-31 12:00:00     0
2012-10-31 11:55:00     0
2012-10-31 11:50:00     0
2012-10-31 11:45:00     2
2012-10-31 11:40:00     0

If i had X=0, the number I would want back here would be 3, because the most recent value matches X, and the next 2 rows also match it.

I don’t have any ID column or anything. I could add one if need be, but I’d like to avoid it.

Answer 1

select count(*) as num
from data_point
where creation_datetime > (
  select max(creation_datetime)
  from data_point
  where data_point <> 0
)

Counts the number of records after the last record that was not your desired value.