SELECT 最后一行，但前提是列值是预期值

Question

My Table

---------------------
id | userid | name
---------------------
0     1       John
1     2       Ellen
2     1       Peter
---------------------

This table shows, that John has changed his name to Peter (same userid - same person) as id =2 is newer record than id= 0

Now... I may want to check whether John is the last name of userid =1. I need to SELECT id of the LAST row WHERE userid =1, but only if name = John . And since name in the last row with userid =1 is not John in this particular case, NULL should be returned. How do I do that? With single SQL command. Thanks

I am using Sqlite3 by the way, some advanced MySQL stuff may not work in my case

Answer 1

Well, one method is to use order by and limit the results to one row:

select (case when name = 'John' then name end)
from t
where userid = 1
order by id desc
fetch first 1 row only;

This uses the fetch first clause because it is Standard SQL. Your database might have another method.