Requête Mysql avancée pour obtenir un enregistrement principal si deux conditions correspondent à différentes lignes d'enregistrements enfants

En effet, comme AsConfused l'a laissé entendre, vous avez besoin de deux jointures à TABLE2 en utilisant des alias

-- both of these are tested :

-- find t1 where it has 2 and 7 in t2

    select t1.*
    from table1 t1
    join table2 ov2 on t1.id=ov2.masterid and ov2.optionValue=2
    join table2 ov7 on t1.id=ov7.masterid and ov7.optionValue=7

-- find t1 where it has 2 and 7 in t2, and no others in t2

select t1.*, ovx.id
    from table1 t1
      join table2 ov2 on t1.id=ov2.masterid and ov2.optionValue=2
      join table2 ov7 on t1.id=ov7.masterid and ov7.optionValue=7
      LEFT OUTER JOIN table2 ovx on t1.id=ovx.masterid and ovx.optionValue not in (2,7)
    WHERE ovx.id is null