Question

我想从数据库中的表中检索最后一个主键插入（ID）的记录，这是我的程序的样子，但是当我运行它时将返回到空白页面。查询错了吗？

<div style="background:steelblue;">
    <form action=saveRecord.jsp> <<----will save the record to other table
        <%
        Class.forName("com.mysql.jdbc.Driver").newInstance();
        Connection conn =     DriverManager.getConnection("jdbc:mysql://localhost:3306/dssps", "root", "admin");
        String query = "select Did,ShipName,Origin,Port1 from decsfinal where   Did=LAST_INSERT_ID()";
        Statement st = conn.createStatement();
        ResultSet rs = st.executeQuery(query);
        if(rs.next()){
        %>

        <label>ID</label>
        <input  name="Did" value="<%=rs.getInt("Did")%>">
        </br>

        <label>Ship Name</label>
        <input  name="ShipName" value="<%=rs.getString("ShipName")%>">
        </br>

        <label>Origin Port</label>
        <input  name="Origin" value="<%=rs.getString("Origin")%>">
        </br>

        <label>Destination Port</label>
        <input  name="Port1" value="<%=rs.getString("Port1")%>">
        </br>

        // here the submit button and close database

Answer 1

您可以使用：

<div style="background:steelblue;">
    <form action=saveRecord.jsp>
        <%
            try {
                Class.forName("com.mysql.jdbc.Driver").newInstance();
                Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/dssps", "root", "admin");
                String query = "select Did, ShipName, Origin, Port1 from decsfinal where Did = LAST_INSERT_ID()";
                Statement st = conn.createStatement();
                ResultSet rs = st.executeQuery(query);
                if (rs.next()) {
                    out.print(rs.getInt(1));
                    out.print(rs.getString(2));
                    out.print(rs.getString(3));
                    out.print(rs.getString(4));
                    //Or you can use
//                            out.print(rs.getInt("Did"));
//                            out.print(rs.getString("ShipName"));
//                            out.print(rs.getString("Origin"));
//                            out.print(rs.getString("Port1"));
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        %>
    </form>
</div>

Answer 2

last_insert_id（）方法正在检索last_id + 1表示如果你的最后一个id是9它正在检索10并在where子句中进行比较，因此没有id等于10你的查询正在检索null，试试这个查询（对我有用）。

select Did,ShipName,Origin,Port1 from decsfinal where Did = Last_insert_id()-1;

OR 如果您的主键（Did）设置为自动增量，则可以使用此查询来获得所需的结果

select max(Did) , ShipName ,Origin,Port1 from decsfinal;

检索上一个Auto Increment主键和输入字段中的视图的记录

2 个答案: