c# - OleDBException 错误插入

Question

我构建了一个 C# 应用程序，您可以在其中登录并注册新帐户。但是，当我单击“新帐户”按钮并填写必填字段时，我会收到以下错误:

vcom.ExecuteNonQuery(); -> OleDBException 未处理。指令 INSERT 包含语法错误。

请参阅下面的代码:

---

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;

namespace Eindopdracht
{
    public partial class maak_account : Form
    {

        OleDbConnection vcon = new OleDbConnection(@"provider= microsoft.jet.oledb.4.0;data source=sample.mdb");

        public maak_account()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            OleDbConnection vcon = new OleDbConnection(@"provider= microsoft.jet.oledb.4.0;data source=sample.mdb");
            vcon.Open();

            string test = string.Format("insert into inlog (PASSWORD, Username, leeftijd, gewicht) VALUES ('" + textBox2.Text + "','" + textBox1.Text + "','" + textBox3.Text + "','" + textBox4.Text + "')");
            OleDbCommand vcom = new OleDbCommand(test, vcon);
            vcom.ExecuteNonQuery();
            MessageBox.Show("Uw gegevens zijn opgeslagen");
            vcom.Dispose();
        }
    }
}

Answer 1

语法错误的原因是因为Password(恰好是列名)是保留关键字。

insert into inlog ([PASSWORD], Username, leeftijd, gewicht)

• MS Access Reserved Keywords

来自 MS Access 文档，

If a reserved word is already in use, you can avoid error messages by surrounding each occurrence of the word with brackets ([ ]). However, the best solution is to change the name to a nonreserved word.

为了进一步改进代码，

• 使用 using 语句正确处置对象
• 使用try-catch正确处理异常
• 参数化值以避免 SQL 注入(inject)

示例，

string connStr = @"provider= microsoft.jet.oledb.4.0;data source=sample.mdb";
string test = "insert into inlog ([PASSWORD], Username, leeftijd, gewicht) VALUES (?, ?, ?, ?)";

using(OleDbConnection vcon = new OleDbConnection(connStr))
{
    using(OleDbCommand vcom = new OleDbCommand(test, vcon))
    {
        vcom.Parameters.AddWithValue("PASSWORD", textBox2.Text);
        vcom.Parameters.AddWithValue("Username", textBox1.Text);
        vcom.Parameters.AddWithValue("leeftijd", textBox3.Text);
        vcom.Parameters.AddWithValue("gewicht", textBox4.Text);
        try
        {
            vcon.Open();
            com.ExecuteNonQuery();
        }
        catch(OleDbException ex)
        {
            // do something with the exception
        }
    }
}

• Using Parameterized Query