重复语句

// A custom DiagnosticsListener SPI implementation
class DuplicateStatements implements DiagnosticsListener {
    @Override
    public void duplicateStatements(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("Duplicate statements: " + ctx.duplicateStatements());
    }
}

// Utility to run SQL on a new JDBC Statement
void run(String sql) {

    // Configuration is configured with the target DataSource, SQLDialect, etc. for instance Oracle.
    try (Connection c = DSL.using(configuration.derive(new DuplicateStatements()))
                           .diagnosticsConnection();
         Statement s = c.createStatement();
         ResultSet rs = s.executeQuery(sql)) {

        while (rs.next()) {
            // Consume result set
        }
    }
}
    // Everything is fine with the first execution
    run("SELECT title FROM book WHERE id = 1");

    // This query is identical to the previous one, differing only in irrelevant white space
    run("SELECT title FROM book WHERE  id = 1");

    // This query is identical to the previous one, differing only in irrelevant additional parentheses
    run("SELECT title FROM book WHERE (id = 1)");

    // This query is identical to the previous one, differing only in what should be a bind variable
    run("SELECT title FROM book WHERE id = 2");

    // Everything is fine with the first execution of a new query that has never been seen
    run("SELECT title FROM book WHERE id IN (1, 2, 3, 4, 5)");

    // This query is identical to the previous one, differing only in what should be bind variables
    run("SELECT title FROM book WHERE id IN (1, 2, 3, 4, 5, 6)");
}