我试图从mu数据库中的某个表中选择行,并根据结果更新表。经过大量的研究,updateString()和updateRow()似乎是可行的方法。这是我的代码,请注意stateStatement类型的全局变量:

public void updateMyRows(Connection conn){
    try {
        int id;
        String firstName, lastName, userName, pwd;
        state = conn.createStatement();
        String sql = "SELECT idP, firstName, lastName, salt FROM PERSON";
        ResultSet rs = state.executeQuery(sql);
        while (rs.next()){
            id = rs.getInt("idP");
            firstName = rs.getString("firstName");
            lastName = rs.getString("lastName");
            userName = UserNamePwd.userNameGen(lastName, firstName, id);
            pwd = UserNamePwd.passWordGen(lastName, firstName, id);
            rs.updateString("userName", userName);
            rs.updateString("pwd", pwd);
            rs.updateRow();
        }
        rs.close();
        state.close();
    } catch (Exception e){
        e.printStackTrace();
    }
}

这样做会导致以下错误:
java.sql.SQLException: Column 'userName' not found.
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
        at com.mysql.jdbc.ResultSetImpl.findColumn(ResultSetImpl.java:1077)
        at com.mysql.jdbc.ResultSetImpl.updateString(ResultSetImpl.java:7788)
        at AddUsersToDB.addUserNamesAndHash(AddUsersToDB.java:79)
        at AddUsersToDB.main(AddUsersToDB.java:96)

“用户名”是我要更新的列之一的确切名称。。。发生什么事?

最佳答案

您需要在查询中选择userNamepwd列,以便这些列在结果集中可用。我可以在这里使用SELECT *来获取所有可用的列,不过您可以将userNamepwd添加到选择列表中。

String sql = "SELECT * FROM PERSON";
ResultSet rs = state.executeQuery(sql);
while (rs.next()) {
    id = rs.getInt("idP");
    firstName = rs.getString("firstName");
    lastName = rs.getString("lastName");
    userName = UserNamePwd.userNameGen(lastName, firstName, id);
    pwd = UserNamePwd.passWordGen(lastName, firstName, id);
    rs.updateString("userName", userName);
    rs.updateString("pwd", pwd);
    rs.updateRow();
}

10-06 00:56