Dynamic SQL Query Doubt

[Kumaran Sowrirajan]

Hi friends
Please give me a solution for my doubt.
I am Creating a dynamic SQL query such that if the user selects any value from the picklist then that I set the value in PreparedStatement using the following statement.
For simplification, I write the simple query but the actual query is big.
I am using Prepared Statement to set the value.
DBSQL Query = "select * from table1 where id=?"

StringBuffer sb = new StringBuffer();
sb.append("select * from table1 where id=?");
ps = con.prepareStatement(sb.toString());
ps.setInt(1,value);
rs = ps.executeQuery();
Suppose if the User did not select any value then I need to return all the values from the table.
DBSQL Query = select * from table1 where id is not null
I do not know how to formulate the prepared statement such that it will match the exact DBSQL Query.
Give me a proper solution how to handle this kind of situation?
Thanks,
Kumaran.S

[Jeroen Wenting]

Your best bet is to build the final query from 2 substrings:
A fixed part "select * from table1 " and a variable part that's either "where id=?" or "where id is not null" based on the selected value for the query.