java - 未获取结果集中的所有行

Question

我使用以下代码从结果集中的数据库获取数据:

DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());   

Connection connection = DriverManager.getConnection(
                    "jdbc:oracle:thin:@host:1521:DB", "User","pass_01");
Statement statement = connection.createStatement();   
resultset = statement.executeQuery("select * from employee"); 
System.out.println("Records Exist "+resultset.next()); 
System.out.println(resultset.getRow());
while (resultset.next()) {
    System.out.println(resultset.getInt(1) + " " +
    resultset.getInt(2) + " " + 
    resultset.getInt(3) + " " + 
    resultset.getString(4));
}

但是尽管数据库表中有两行，但我只得到一行。我在这里缺少什么？

Answer 1

这是因为您在循环之前调用rs.next()。它返回一个 boolean 值，并且由于该语句，一行将失去打印的机会。

Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@host:1521:DB", "User","pass_01");
Statement statement = connection.createStatement();   
resultset = statement.executeQuery("select * from employee"); 
while (resultset.next()) {
    System.out.println(resultset.getInt(1) + " " +
    resultset.getInt(2) + " " + 
    resultset.getInt(3) + " " + 
    resultset.getString(4));
}