CREATE TABLE college
(
  id       SERIAL PRIMARY KEY,
  SCHOOL   VARCHAR(100),
  CColor   VARCHAR(100),
  CCmascot VARCHAR(100)
);

CREATE TABLE mats
(
  id                SERIAL PRIMARY KEY,
  CColor            VARCHAR(100),
  CCNAME            VARCHAR(100)
);

select
    m.ccname, m.ccolor
from
    mats m
inner join
    college c
on
    c.ccolor = m.ccolor
where
    c.school = @myVariable

select
  college.ccolor
from
  college inner join mats
    on college.id = mats.college_id
where
  mats.ccname = "<<COLOUR_DESIRED>>";

SELECT college.CColor FROM college
    INNER JOIN mats ON college.CColor = mats.CColor
    AND mats.CColor = 'your query'