如何更新数据库记录 vs12 C#

Question

您好，我在为我的网站制作更新按钮时遇到问题我已经尝试了很多方法，但似乎无法弄清楚。我希望用户输入他们希望更新的客户端的 ID 号，然后根据他们希望更改的列填写文本框。

这是我的代码：

private static OleDbConnection GetConnection()
{
    String connString;
    connString = @"Provider=Microsoft.JET.OLEDB.4.0;Data Source=C:\Users\Wisal\Documents\Visual Studio 2012\WebSites\WebSite3\registration-Db.mdb";

    return new OleDbConnection(connString);
}

protected void clientUpdate_Click(object sender, EventArgs e)
{
    OleDbConnection cn = new OleDbConnection("Provider=Microsoft.JET.OLEDB.4.0;Data Source=C:/Users/Wisal/Documents/Visual Studio 2012/WebSites/WebSite3\registration-Db.mdb");

    cn.Open();
    OleDbCommand cmd = new OleDbCommand("(Update client set id = " + txt_id.Text + " ,[name] ='" + txt_name.Text + " ,[password] ='" + txt_password.Text +" where id= '" + txt_id.Text + "",cn);
    cmd.ExecuteNonQuery();
    cn.Close();
    }      
}

我也试过这个：

private static OleDbConnection GetConnection()
{
    String connString;
    connString = @"Provider=Microsoft.JET.OLEDB.4.0;Data Source=C:\Users\Wisal\Documents\Visual Studio 2012\WebSites\WebSite3\registration-Db.mdb";

    return new OleDbConnection(connString);

}

protected void clientUpdate_Click(object sender, EventArgs e)
{
    OleDbConnection myConnection = GetConnection();

    myConnection.Open();
    OleDbCommand cmd = new OleDbCommand("(Update client set id = " + txt_id.Text + " ,[name] ='" + txt_name.Text + " ,[password] ='" + txt_password.Text +" where id= '" + txt_id.Text + "",myConnection);
    cmd.ExecuteNonQuery();
    myConnection.Close();
    }
}

有了这个，我得到了 "Syntax error in union query."

我也试过这个：

protected void clientUpdate_Click(object sender, EventArgs e)
{
    OleDbConnection myConnection = GetConnection();

    myConnection.Open();
    OleDbCommand cmd = new OleDbCommand("Update client set [name] = ? [password] = ? where id= ?", myConnection);
    cmd.Parameters.AddWithValue("", txt_id.Text);
    cmd.Parameters.AddWithValue("", txt_name.Text);
    cmd.Parameters.AddWithValue("", txt_password.Text);
    cmd.ExecuteNonQuery();
    myConnection.Close();
    }

    }

Answer 1

你的单引号不匹配？

您的 id 字段是 int 还是 string 类型？我假设它是int类型的。而且您不需要更新 id 字段，因为它与 where 子句中的值相同。

试试这个：

OleDbCommand cmd = new OleDbCommand("Update client set [name] ='" + txt_name.Text + "' ,[password] ='" + txt_password.Text +"' where id= " + txt_id.Text,myConnection);

Answer 2

我稍微更新了你的代码：

private static OleDbConnection GetConnection()
{
    var connString = @"Provider=Microsoft.JET.OLEDB.4.0;Data Source=C:\Users\Wisal\Documents\Visual Studio 2012\WebSites\WebSite3\registration-Db.mdb";

    return new OleDbConnection(connString);
}

protected void clientUpdate_Click(object sender, EventArgs e)
{
    using(var myConnection = GetConnection())
    {
        myConnection.Open();
        // You should be using a parameterized query here
        using (var cmd = new OleDbCommand("Update client set [name] = ?, [password] = ? where id = ?", myConnection))
        {
            cmd.Parameters.AddWithValue("name", txt_name.Text);
            cmd.Parameters.AddWithValue("password", txt_password.Text);
            cmd.Parameters.AddWithValue("id", txt_id.Text);

            cmd.ExecuteNonQuery();
        }
    }
}

在一次性物品周围使用方块
检查您的 SQL，如果这是您的主键，则无需更新 id 并注意单引号。请改用参数化查询。

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