Question

I have an sql table of PlayerTrial that holds, well, player trials.

---PlayerTrials Basic Layout---
int id
int playerid
bool flagA
bool flagB
bool flagC

I want to determine the % of trials a player has done with flags B and C set.

To do so, I know I have to:

1) Select the total trials by a single player

SELECT COUNT( * ) from playertrial WHERE playerid = _

2) Select the total trials with flagB and flagC true

SELECT COUNT( * ) from playertrial WHERE playerid = _ AND flagB = true AND flagC = true

3) divide 2 by 1 to determine the % of trials with flags B+C set

brain explode.

I know how to do the individual queries for both one and two. And of course I could store them in a temporary table or something. But I’m sure there’s a way to join them into one query, and I have fried my brain trying all the SQL combos I know such that I don’t have a clue what to try next. Any ideas?

Answer 1

SELECT BCCount, TotalCount, BCCount/TotalCount as Percentage
    FROM (SELECT SUM(CASE WHEN flagB=true AND flagC=true THEN 1 ELSE 0 END) AS BCCount,
                 COUNT(*) as TotalCount
              FROM playertrial
              WHERE playerid = _) t