java.sql.SQLTransactionRollbackException : At least one parameter to the current statement is uninitialized 异常

Question

我正在尝试从数据库(在我名为“vsota”的项目中)获取整数值的总和，并将其显示在 JLabel 中(在我名为“vpd”的项目中)。并且提供的代码不起作用。这是异常(exception):

Error: java.sql.SQLTransactionRollbackException: At least one parameter to the current statement is uninitialized.

try {
    stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE);
    String sql = "SELECT SUM(vsota) FROM Vse WHERE vsota = ?";
    rs = stmt.executeQuery(sql);

    rs.next();
    int stevilo = rs.getInt("vsota");
    String vsota = Integer.toString(stevilo);

    vpd.setText(vsota);

} catch (SQLException ex) {
    Logger.getLogger(ZačetniObrazec.class.getName()).log(Level.SEVERE, null, ex);
}

Answer 1

Error: java.sql.SQLTransactionRollbackException: At least one parameter to the current statement is uninitialized.

您的 String 使用参数 vsota = ? 因此您需要使用 PreparedStatement 而不是 Statement能够为其定义一个值。

PreparedStatement ps = null;
ResultSet rs = null;

try{
    ps = con.prepareStatement(sql);
    ps.setInt(1, vSotaValue); //parameters are 1-based

    rs = ps.execute();
} finally {
    if(rs != null) try{rs.close();} catch(SQLException e){}
    if(ps != null) try{ps.close();} catch(SQLException e){}
}