Question

I’d like to combine several queries into as few as possible. This is for a video game I’m writing.
Note
-spawn_id is the id of an entity that creates the bad guy on the level at a given place on a map.
-* from spawns includes the spawn_id, max quantity of bad guys to spawn(quantity), and the type of bad guy to spawn (mob_id)to spawn them and an ID to tell it what type of bad guy to spawn
the game is online so Id rather minimize the number of queries

It would be nice if I could subtract count (number already in game) from quantity(maximum quantity to have in game) where spawn ID are the same and return that all together

Would be even better if I could return the spawn ID quantity to spawn and the type of bad guy together as one row like this

SELECT spawn_id, COUNT(*) as ‘count’ FROM game_moblist GROUP BY spawn_id”
returns…

spawn_id count
======== =====
1         2

TABLE spawns contains

spawn_id quantity mob_id level
======== ======== ====== =====
1        5        1      2

mob_id poitns to TABLE mobs which has

mob_id ...stats for mob_id
====== ===================
1      unique stats for mob#1

I’d like to return something like this:

spawn_id   quantity_to_spawn   mob_id   ...stats for mob_id
========   =================   ======
1          3                   1        unique stats for mob#1

which means I must insert 3 rows selected from mobs which I don’t mind doing a second query for so I can multiply stats by level to create a bad guy in the game that is level 2… essentially level 2 means the stats are twice as high as the number stored in ‘mobs’ table

Here is my code so far I could finish it but I’d rather try to reduce the number of queries first.

    sql= "SELECT spawn_id, COUNT(*) as 'count' FROM game_moblist  GROUP BY spawn_id"
       connection.query(sql, function(err, spawncount, fields) {
          sql= "SELECT  * FROM spawns"
          connection.query(sql, function(err, spawns, fields) {
             for (i=0;i<spawns.length;i++){
                if (spawns[i].next_spawn < new Date().getTime()){
               for (j=0;spawncount.length;j++){
                      if (spawncount[j].spawn_id ==spawns[i].spawn_id&&spawncount[j].count<spawns[i].quantity){
                         quantity_to_spawn = spawns[i].quantity -spawncount[j].count
                         //fetch spawns[i].mob_id mob from mobs table
                         for(k=0;k<quantity_to_spawn;k++){
                         //multiply for level
                         //insert into moblist
                         }
                      }
                   }
                }
             }
          });
       });

Answer 1

SELECT 
 spawn_id,
 quantity - COUNT(game_moblist.(spawn_id)) AS quantity_to_spawn,
 mobs.*
FROM spawn_contains
LEFT JOIN mobs USING (mob_id)
LEFT JOIN game_moblist USING (spawn_id)
GROUP BY spawn_id