JAVA JDBC mySql Prepared statement 更新查询

2022-01-17 00:00:00 sql-update mysql prepared-statement jdbc java

我正在尝试执行以下代码

I am trying to execute the following code 

package jdbclesson;

import java.sql.*;

public class PreparedQuery {

public static void main(String[] args) throws Exception
{
    String url              = "jdbc:mysql://localhost:3306/alien?useSSL=false";
    String uname            = "root";
    String pass             = "ma123";
    String query            = "UPDATE student SET username= ? where userid= ? ";
    PreparedStatement stmt  = null;


    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection(url, uname, pass);
    stmt = con.prepareStatement(query);

    stmt.setString(1, "tina");
    stmt.setInt(2, 6);


    int rs = stmt.executeUpdate(query);

    System.out.println(rs);
    stmt.close();
    con.close();

}

}

但出现以下错误

线程main"中的异常com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: 你有一个SQL 语法错误；检查与您对应的手册MySQL 服务器版本，以便在 '? 附近使用正确的语法在哪里用户 ID=?在第 1 行

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '? where userid=?' at line 1

我的数据库只有 1 个表 student 有 2 列用户 ID 和用户名以及 10 行我缺少什么

My database has only 1 table student with 2 columns userid and username and 10 rows what m i missing

推荐答案

试试:

int rs = stmt.executeUpdate();

代替:

int rs = stmt.executeUpdate(query);

executeUpdate() 运行准备好的语句的查询，这是您想要的.executeUpdate(query) 运行传递给该方法的查询.您收到错误是因为您传递了带有错误的 SQL(包含?).

executeUpdate() runs the query of the prepared statement, which is what you want. executeUpdate(query) runs the query passed to the method. You were getting the error because you were passing an SQL with errors (contains ?).

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