PreparedStatement IN clause alternatives?

Question

What are the best workarounds for using a SQL IN clause with instances of java.sql.PreparedStatement, which is not supported for multiple values du

Answer 1

No simple way AFAIK. If the target is to keep statement cache ratio high (i.e to not create a statement per every parameter count), you may do the following:

1. create a statement with a few (e.g. 10) parameters:

   ... WHERE A IN (?,?,?,?,?,?,?,?,?,?) ...

2. Bind all actuall parameters

   setString(1,"foo"); setString(2,"bar");

3. Bind the rest as NULL

   setNull(3,Types.VARCHAR) ... setNull(10,Types.VARCHAR)

NULL never matches anything, so it gets optimized out by the SQL plan builder.

The logic is easy to automate when you pass a List into a DAO function:

while( i < param.size() ) {
  ps.setString(i+1,param.get(i));
  i++;
}

while( i < MAX_PARAMS ) {
  ps.setNull(i+1,Types.VARCHAR);
  i++;
}