query with multiple IN parameters

Hello all,
A beginner in Java although have couple of years using Stata(statistical software) and its odbc. I will run a query which asks users to input user_id.
select distinct doc_id from documents where user_id=b. The user has to input b. Based on that, the query will generate some integers like this

doc_id
2
3
4

Next I need to transform the column values horizontally separated by comma. In Stata, I would do something called levelsof. So, I have now
2,3,4

I need to take 2,3,4 and put it in my next final query like this..
select count(*) from readership where source_id in (2,3,4)

Can this be done in Java?? Any help will be highly appreciated...

Thanks..

This is purely a SQL query, not a Java thing.
A single one at that.

Code:

---

SELECT count(*)
FROM readership
WHERE source_id IN
  (SELECT distinct doc_id etc etc)

---

This assumes you don't need the intermediate step.

Thanks.. but unfortunately each query has to be performed on different database. So, basically I need to get the distinct doc_id from one database and use that to get counts from another database. Well, basically what I am looking for is the way to do using JDBC api. I see that you could do this if I wanted a placeholder for each IN parameter, I could use ("?").
select count(*) from readership where source_id=?
psmt.setLong(1,1234)

My question is what is the method if I need a placeholder for multiple integers like
select count(*) from readership where source_id in (1,2,3,4,6) // not a single integer represented by "?" but bunch of integers separated by comma. Please let me know if you need more detail. Thanks.

Assuming the number of ids in the IN clause is fairly limited (Oracle, for example, has a limit of around 1000), then the usual technique is to either concatenate the IN clause (if they are likely to vary a lot), which makes each query unique, or to build the IN clause for a PreparedStatement something along the lines of:

Code:

---

for (each id) {
  if (firstId) {
      preparedStatementString.append("?"); 
  } else {
      preparedStatementString.append(",?"); 
  }
}

---

then assign them:

Code:

---

for (each id) {
  ps.setInt(<loopIndex>, id);
}

---

Note, of course, that the above is not copy/paste material.