Question

Quick one,

I have a table, with the following structure

id  lid  taken
1   1    0
1   1    0
1   1    1
1   1    1
1   2    1

Pretty simply so far right?

I need to query the taken/available from the lid of 1, which should return

taken  available
2      2

I know I can simply do two counts and join them, but is there a more proficient way of doing this rather than two separate queries?

I was looking at the following type of format, but I can not for the life of me get it executed in SQL…

SELECT
   COUNT(case taken=1) AS taken, 
   COUNT(case taken=0) AS available FROM table
WHERE 
   lid=1

Thank you SO much.

Answer 1

Your query is correct just needs juggling a bit:

SELECT
   SUM(case taken WHEN 1 THEN 1 ELSE 0 END) AS taken, 
   SUM(case taken WHEN 1 THEN 0 ELSE 1 END) AS available FROM table
WHERE 
   lid=1

Alternatively you could do:

SELECT
   SUM(taken) AS taken, 
   COUNT(id) - SUM(taken) AS available 
FROM table
WHERE 
   lid=1