Question

我试图对表医生进行更新查询。表的主键定义为复合主键（deptid，docid）。我想要做的是根据deptid和docid（通过另一个查询）更新字段名称，资格和时间。我相信我做的事情非常愚蠢，但我找不到它。有人可以帮忙吗？

String did= request.getParameter("text1");
String dname = request.getParameter("text2");
String desig = request.getParameter("text3");
String qualification = request.getParameter("text4");
String time = request.getParameter("text5");

String className = "com.mysql.jdbc.Driver";
String url = "jdbc:mysql://192.168.10.13";
String user = "root";
String password = "";

PreparedStatement ps;
ResultSet rs;

try {
    Class.forName(className);                
    Connection con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/webhospital","root","");
    //        PreparedStatement prepStmt = (PreparedStatement) conn.prepareStatement("Select * from tbl_userinfo");
    ps = (com.mysql.jdbc.PreparedStatement) con.prepareStatement("update doctors set Designation=?,Qualification=?,Time= ? where deptid =? and docid IN(select docid from doctors where doctorname='dname';)");
    ps.setString(1, did);
    ps.setString(3,desig);
    ps.setString(4,qualification);
    ps.setString(5,time);
    ps.executeUpdate();
}  catch (ClassNotFoundException cx) {
    out.println(cx);
} catch (SQLException ex) {
    Logger.getLogger(MysqlInsertServlet.class.getName()).log(Level.SEVERE, null, ex);
}

Answer 1

 ps = (com.mysql.jdbc.PreparedStatement) con.prepareStatement("update doctors set Designation=?,Qualification=?,Time= ? where deptid =? and docid IN(select docid from doctors where doctorname='dname';)");
            ps.setString(1, did);
            ps.setString(3,desig);
            ps.setString(4,qualification);
            ps.setString(5,time);

你有4个问号，但设置错误，为什么你不设置如下：

ps.setString(1, desig);
                ps.setString(2,qualification);
                ps.setString(3,time);
                ps.setString(4,deptId);

Supplying Values for PreparedStatement Parameters

您必须提供值代替问号占位符（如果   你可以执行PreparedStatement对象之前有任何一个。做   这可以通过调用其中一个setter方法来定义   PreparedStatement类。以下陈述提供了两个   名为updateSales的PreparedStatement中的问号占位符：

updateSales.setInt（1，e.getValue（）。intValue（））;   updateSales.setString（2，e.getKey（））;

每个setter方法的第一个参数指定了   问号占位符。在此示例中，setInt指定第一个   placeholder和setString指定第二个占位符。

Answer 2

您的查询中需要进行一项更改

"where doctorname='dname';)" ==＆gt;＆gt; "where doctorname='"+dname+"';)"

Answer 3

我认为如果不编辑代码，最好向您展示一个简单的例子。

    PrintWriter out = response.getWriter();
    String Title = request.getParameter("Title");
    String Artist = request.getParameter("Artist");
    String Country = request.getParameter("Country");
    String price = request.getParameter("price");
    String Year = request.getParameter("Year");

    try {
        //loading driver 

        Class.forName("org.apache.derby.jdbc.EmbeddedDriver");

        //creating connection with the database 
        Connection con = DriverManager.getConnection("jdbc:derby://localhost:1527/sample", "app", "app");

        PreparedStatement ps = con.prepareStatement("update COMPACT_DISK set TITLE=?,ARTIST=?,COUNTRY=?,PRICE=?,YEARS=? where TITLE=?");

        ps.setString(1, Title);
        ps.setString(2, Artist);
        ps.setString(3, Country);
        ps.setString(4, price);
        ps.setString(5, Year);
        ps.setString(6, Title);
        int i = ps.executeUpdate();
        if (i > 0) {
            out.println("Compact disk successfully inserted");
        }
    } catch (Exception se) {
        out.println("Error Occured : \n" + se.getLocalizedMessage());
        se.printStackTrace();
    }

更新java JDBC + mysql数据库的查询

3 个答案: