使用 *（不是列名）时无法获取 SQL 查询结果

Question

我只能在使用 select columnname from tablename 时从 SQL 查询执行中获取结果，但在使用 select * from tablename 时不能获得结果

public static void connectAndExecute(String host, String uName, String uPass, String sqlQuery) {
    try { 
        DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
    } catch (SQLException e) {          
        e.printStackTrace();
    }

    try {
        Connection con=DriverManager.getConnection(host, uName, uPass);
        String[] conData = null;
        Statement stmt = null;      

        try {
            stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery(sqlQuery);
            /*this is the place of my problem*/
        } 
        catch (SQLException e) {            
            e.printStackTrace();
        }
    }
    catch (SQLException err) {
        System.out.println(err.getMessage());
    }
}

Answer 1

使用ResultSet.class 方法来获得所需的结果。您可以给出列名或列索引。

getInt(int columnIndex)

获取当前行中指定列的值 这个 ResultSet 对象在 Java 编程语言中是一个 int。

getString(int columnIndex)

获取当前行中指定列的值 在 Java 编程语言中将此 ResultSet 对象作为字符串。

以下是您可以如何实现它：

while(rs.next()){ 
//Retrieve by column index 
int id = rs.getInt(1); //assume id is at 1st index
int age = rs.getInt(4); //assume age is at 4th index
String first = rs.getString(2); // assume first name is at 2nd index
String last = rs.getString(3); // assume last name is at 3rd index
//Display values 
System.out.print("ID: " + id); System.out.print(", Age: " + age); System.out.print(", First: " + first); System.out.println(", Last: " + last);
System.out.println(" End of one row"); 
}