即使在蟾蜍中运行相同查询时，即使同一查询返回一行，Prepared Statement也无法正常工作

Question

I am trying to get a row from DB using preparedStatement using a code which somewhat looks like this:

PreparedStatement preparedStatement = null;
Connection con = new Connection ()  //pseudo Code added here
String query = "select * from abc where a=? and b=? and c=?";

preparedStatement = con.prepareStatement(query);

preparedStatement.setString(1,"x");

preparedStatement.setString(2,"y");

preparedStatement.setString(3,String.valueOf('Z'));

ResultSet resultset = preparedStatement.executeQuery();

if(resultset.next() == false)
{
  throw new exception("No records fetched");
}

but the following query when executed via TOAD, returns a row:

select * from abc where a='x' and b='y' and c='z';

What am I doing wrong here? (The third condition in where clause is a char).

Answer 1

The two queries are different, in TOAD you're issuing

select * from abc where a='x' and b='y' and c='z'

whereas from your prepared statement you're doing the equivalent of:

select * from abc where a='x' and b='y' and c='Z'

z is not the same as Z

You don't need to specify Oracle CHAR parameters as Java char in the setParameter, so changing

preparedStatement.setString(3,String.valueOf('Z'));

to either

preparedStatement.setString(3,"z");

or

preparedStatement.setString(3,String.valueOf('z'));

will probably work.