重复的语句

// A custom DiagnosticsListener SPI implementation
class RepeatedStatement implements DiagnosticsListener {
    @Override
    public void repeatedStatements(DiagnosticsContext ctx) {

        // The statement that is being executed and which has duplicates
        System.out.println("Actual statement: " + ctx.actualStatement());

        // A normalised version of the actual statement, which is shared by all duplicates
        // This statement has "normal" whitespace, bind variables, IN-lists, etc.
        System.out.println("Normalised statement: " + ctx.normalisedStatement());

        // All the duplicate actual statements that have produced the same normalised
        // statement in the recent past.
        System.out.println("Repeated statements: " + ctx.repeatedStatements());
    }
}

// Configuration is configured with the target DataSource, SQLDialect, etc. for instance Oracle.
try (Connection c = DSL.using(configuration.derive(new RepeatedStatement()))
                       .diagnosticsConnection();
     Statement s1 = c.createStatement();
     ResultSet a = s1.executeQuery("SELECT id FROM author WHERE first_name LIKE 'A%'")) {

    while (a.next()) {
        int id = a.getInt(1);

        // This query is run once for every author, when we could have joined the author table
        try (PreparedStatement s2 = c.prepareStatement("SELECT title FROM book WHERE author_id = ?")) {
            s2.setInt(1, id);

            try (ResultSet b = s2.executeQuery()) {
                while (b.next())
                    System.out.println("ID: " + id + ", title: " + b.getString(1));
            }
        }
    }
}