java - 查询 JDBC Java

Question

我的 java/jdbc 代码有问题。

参数索引超出范围（2 个参数，即 1）

代码：

                Connection c = null;
                MySQL MySQL = new MySQL(Host, Port, Database, Username, Password);
                c = MySQL.open();  
              Player player = (Player) sender;
               String zapytanie = "UPDATE `?` SET `tag`=? WHERE   `name`='?';";
               PreparedStatement ps = c.prepareStatement( zapytanie );
               ps.setString(1, Tabel);
               ps.setString(2, red);
               ps.setString(3, player());
               ps.executeUpdate(); //Executes the query
               ps.close(); //Closes the query
               c.close();

Answer 1

final String zapytanie = "UPDATE " + Table + " SET tag = ? WHERE name = ?";

• ?不需要引号
• JDBC 不需要任何SQL 语句;之后
• 占位符?只能用于列值