code: public void setTransactionIsolation(final int level) throws SQLException {
          String query = "SET SESSION TRANSACTION ISOLATION LEVEL";
          switch (level) {
              case Connection.TRANSACTION_READ_UNCOMMITTED:
                  query += " READ UNCOMMITTED";
                  break;
              case Connection.TRANSACTION_READ_COMMITTED:
                  query += " READ COMMITTED";
                  break;
              case Connection.TRANSACTION_REPEATABLE_READ:
                  query += " REPEATABLE READ";
                  break;
              case Connection.TRANSACTION_SERIALIZABLE:
                  query += " SERIALIZABLE";
                  break;
              default:
                  throw SQLExceptionMapper.getSQLException("Unsupported transaction isolation level");
          }
          try {
              protocol.executeQuery(queryFactory.createQuery(query));
          } catch (QueryException e) {
              throw SQLExceptionMapper.get(e);
          }
      }
docs: Attempts to change the transaction isolation level for this <code>Connection</code> object to the one given. The
  constants defined in the interface <code>Connection</code> are the possible transaction isolation levels.
  <p/>
  <B>Note:</B> If this method is called during a transaction, the result is implementation-defined.
  
  @param level one of the following <code>Connection</code> constants: <code>Connection.TRANSACTION_READ_UNCOMMITTED</code>,
  <code>Connection.TRANSACTION_READ_COMMITTED</code>, <code>Connection.TRANSACTION_REPEATABLE_READ</code>,
  or <code>Connection.TRANSACTION_SERIALIZABLE</code>. (Note that <code>Connection.TRANSACTION_NONE</code>
  cannot be used because it specifies that transactions are not supported.)
  @throws java.sql.SQLException if a database access error occurs, this method is called on a closed connection or
  the given parameter is not one of the <code>Connection</code> constants
  @see java.sql.DatabaseMetaData#supportsTransactionIsolationLevel
  @see #getTransactionIsolation