How to get number of PK used as FK? How to get number of PK used as FK?

Table 1 has a column ID (PK).
Table 2 &amp; 3 has a column ID (FK - refers Table 1 PK).

How to get Value 1 (PK) has used in table 2 &amp; 3 or not without referring table 2 or 3 ?
SELECT id 
FROM table1
WHERE EXISTS (SELECT 1
              FROM table2
              WHERE table1.id = table2.id)
  AND /* OR */
      EXISTS (SELECT 1
              FROM table3
              WHERE table1.id = table3.id)


When you need ids which are present both in table1 and table3, use AND.

When you need ids which are present at least in one of these tables, use OR.