I have a lot of SQL queries like this:

SELECT o.Id, o.attrib1, o.attrib2 FROM table1 o WHERE o.Id IN (
  SELECT DISTINCT Id FROM table1, table2, table3 WHERE ...
)

These queries have to run on different database engines (MySql, Oracle, DB2, MS-Sql, Hypersonic), so I can only use common SQL syntax.

Here I read, that with MySql the IN statement isn't optimized and it's really slow, so I want to switch this into a JOIN.

I tried:

SELECT o.Id, o.attrib1, o.attrib2 FROM table1 o, table2, table3 WHERE ...

But this does not take into account the DISTINCT keyword.

Question: How do I get rid of the duplicate rows using the JOIN approach?