Question

I need help with a SQL query.

I have a table with a ‘state’ column. 0 means closed and 1 means opened.

Different users want to be notified after there have been x consecutive 1 events.

With an SQL query, how can I tell if the last x rows of ‘state’ = 1?

Answer 1

If, for example, you want to check if the last 5 consecutive rows have a state equals to 1, then here’s you could probably do it :

SELECT IF(SUM(x.state) = 5, 1, 0) AS is_consecutive 
FROM (
    SELECT state 
    FROM table 
    WHERE Processor = 3
    ORDER BY Status_datetime DESC
    LIMIT 5
) as x

If is_consecutive = 1, then, yes, there is 5 last consecutive rows with state = 1.

Edit : As suggested in the comments, you’ll have to use ORDER BY in your query, to get the last nth rows.

And for more accuracy, since you have a timestamp column, you should use Status_datetime to order the rows.