Question

在IntelliJ中，我试图将新记录添加到MySQL表中，但是，当我启动服务器（Tomcat 9.0.141）时，它会添加双记录。当我刷新浏览器时，它只添加一次，而当我启动服务器（Tomcat）时，它添加两次。我到处都在寻找答案，即使是在FB上也是如此，没人知道该说些什么。请帮助。这是我的整个servlet：

@WebServlet(value = "/sqlu")
public class MySQLServletUpdate extends HttpServlet {


protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/plain; charset=utf-8");

    try{
        Driver driver = new com.mysql.cj.jdbc.Driver();
        DriverManager.registerDriver(driver);
        Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/AppJEE?useSSL=false&characterEncoding=utf8&useJDBCCompianttimezoneShift=true&useLegacyDatetimecode=false&serverTimezone=UTC", "root", "password");

        PreparedStatement pstmt = connection.prepareStatement("INSERT INTO user VALUES (null, ?, ?, ?)");
        pstmt.setString(1, "Mark");
        pstmt.setString(2, "Marks");
        pstmt.setString(3, "Mar");

        if (pstmt.executeUpdate() > 0) {
            response.getWriter().println("Record added");
        }


    } catch (SQLException e) {
        e.printStackTrace();
    }
}
}

当我在phpMyAdmin中查看表时，会出现一些错误：

    Warning in ./libraries/sql.lib.php#613
 count(): Parameter must be an array or an object that implements Countable

Backtrace

./libraries/sql.lib.php#2128: PMA_isRememberSortingOrder(array)
./libraries/sql.lib.php#2079: PMA_executeQueryAndGetQueryResponse(
array,
boolean true,
string 'AppJEE',
string 'uzytkownik',
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
string '',
string './themes/pmahomme/img/',
NULL,
NULL,
NULL,
string 'SELECT * FROM `uzytkownik`',
NULL,
NULL,
)
./sql.php#221: PMA_executeQueryAndSendQueryResponse(
array,
boolean true,
string 'AppJEE',
string 'uzytkownik',
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
string '',
string './themes/pmahomme/img/',
NULL,
NULL,
NULL,
string 'SELECT * FROM `uzytkownik`',
NULL,
NULL,
)
./index.php#53: include(./sql.php)

这是我桌子上的一个视图1

这是我桌子上的另一个视图2

Answer 1

我通过将Tomcat服务器设置为仅运行而无需立即加载页面来解决我的问题。当Tomcat运行时，我手动转到浏览器并加载页面，然后仅添加一次记录。

插入以添加双记录MySQL语句

1 个答案: