Question

此代码在下面标记的行上引发了错误，有人可以指出正确的方向为什么引发错误吗？

 SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["LocalSqlServer"].ConnectionString);
    SqlDataAdapter dadapter;
    DataSet dset; 
    string sql = "SELECT * from  SocoetyMaintan";

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            dadapter = new SqlDataAdapter(sql, con);
            dset = new DataSet();
            dadapter.Fill(dset);
            DropDownList1.DataSource = dset.Tables[0];
            DropDownList1.DataTextField = "FullName";
            DropDownList1.DataValueField = "Id";
            DropDownList1.DataBind();
            GridViewBind();
        }
    }
      protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            GridViewBind();
        }
        public void GridViewBind()
        {
            dadapter = new SqlDataAdapter("SELECT * from SocoetyMaintan where Id=" + DropDownList1.SelectedValue + "", con);
            dset = new DataSet(); //Throwing Error Here
            dadapter.Fill(dset);
            GridView1.DataSource = dset.Tables[0];
            GridView1.DataBind();

Answer 1

在这里，您忘记了将DropDownList1.SelectedValue转换为字符串或int数据库中的任何内容。因此，请按照以下步骤进行操作。例如，

dadapter = new SqlDataAdapter("select * from SocoetyMaintan where Id='" + DropDownList1.SelectedValue.ToString() + "';", con);

Answer 2

它认为您在e.Message.Data中缺少引号。

Id=

顺便说一句。您绝对不应允许用户直接输入查询。查找“ SQL注入”。

Answer 3

您的书写方式可能会出错。尝试以下

方法1：

LocalSettings

方法2：（首选）

SqlDataAdapter dadapter = new SqlDataAdapter(string.Format("SELECT * FROM SocoetyMaintan WHERE Id = '{0}'",DropDownList1.SelectedValue), con);

Answer 4

1）只需尝试如下更改查询

@objc func checkForReachability(notification:NSNotification)
    {
        let reachability = notification.object as! Reachability
        switch reachability.connection {
        case .wifi:
            print("Reachable via WiFi")
        case .cellular:
            print("Reachable via Cellular")
        case .none:
            print("Network not reachable")
        }
    }

注意：更好地在查询中使用准备好的语句。

dadapter = new SqlDataAdapter("SELECT * from SocoetyMaintan where Id='" + DropDownList1.SelectedValue + "'", con);

2）尝试设置dadapter = new SqlDataAdapter("SELECT * from SocoetyMaintan where Id=@Id", con); dadapter.SelectCommand.Parameters.AddWithValue("@Id", DropDownList1.SelectedValue); => asp:GridView和DataSourceID="GridDataSource" => asp:SqlDataSource

关键字“选择”附近的语法不正确。如何在此代码中解决

4 个答案: