gistfile1.txt

Tables:

thing
thingid, thingname
10, athing
11, bthing
12, cthing

entity
entityid, entityname, thingid
100, someentity, 10
101, someentity, 11
102, someentity, 12
103, someotherentity, 12

value
valueid, entityid, value
1000, 100, 13
1001, 100, 14
1002, 102, 33
1003, 103, 55
1004, 102, 55
1005, 101, 33

Getting the top entities by the number of values:

select t.thingname,e.entityname,v.entityid,count(*) from value v
left join entity e on v.entityid=e.entityid
left join thing t on t.thingid=e.thingid
group by v.entityid order by count(*) desc;

athing, someentity, 100, 2
cthing, someentity, 102, 2
bthing, someentity, 101, 1
cthing, someotherentity, 103, 1

How to get the top things by their corresponding number of values?

cthing, 3
athing, 2
bthing, 1


Creating test setup:

create database thingtest;  
use thingtest;
create table thing (thingid int, thingname varchar(32));
create table entity (entityid int, entityname varchar(32), thingid int);
create table value (valueid int, entityid int, value int);
insert into thing values (10,'athing'),(11,'bthing'),(12,'cthing');
insert into entity values (100,'someentity',10),(101,'someentity',11),(102,'someentity',12),(103,'someotherentity',12);
insert into value values (1000,100,13),(1001,100,14),(1002,102,33),(1003,103,55),(1004,102,55),(1005,101,33);