c# - 数据绑定下拉列表

Question

当我尝试数据时 dropdownlist，得到了这个：system.data.datarowview
我做错了什么？

 string strQuery = "Select Item FROM Calendar Where UserD="Test";
 SqlConnection myConn;
 SqlDataAdapter sqlDa = new SqlDataAdapter(strQuery,myConn);
 DataTable sqlTa = new DataTable("Test");
 da.Fill(sqlTa);
 ddlList.DataSource = sqlTa;
 ddlList.DataBind();

Answer 1

string strQuery = "Select Item FROM Calendar Where UserD='Test'";

请注意，您需要在字符串周围使用单引号，因为在您的代码中您从未完成初始字符串，因此其余代码只是成为 strQuery 的一部分。

另外如果以后带回多个字段，在绑定下拉列表时需要指定数据库中哪个字段是值，哪个是显示的文本。

ddlList.DataSource = sqlTa;
ddlList.DataValueField = "ValueFieldFromDatabaseResults";
ddlList.DataTextField = "ShownTextFieldFromDatabaseResults";
ddlList.DataBind();

Answer 2

您需要告诉它哪些字段用作值和文本。

ddlList.DataSource = sqlTa;
ddlList.DataValueField = "ValueField";
ddlList.DataTextField = "TextField";
ddlList.DataBind();

而且您的 select 语句缺少一个“。它应该是：

"Select Item FROM Calendar Where UserD='Test'"

一个例子是：

正如 ryan 指出的那样，如果您要撤回一个领域，那么您可以这样做：

        DataTable dtTable = new DataTable();

        try
        {
            using (SqlConnection sqlConnection = new SqlConnection("Your connection"))
            {
                using (SqlCommand sqlCommand = new SqlCommand("Select Item FROM Calendar Where UserD='Test'", sqlConnection))
                {
                    sqlConnection.Open();

                    using (SqlDataReader sqlDataReader = sqlCommand.ExecuteReader())
                    {
                        dtTable.Load(sqlDataReader);
                        sqlDataReader.Close();
                    }
                }
            }
        }
        catch (Exception error)
        {
            throw error;
        }

        ddlList.DataSource = dtTable;
        ddlList.DataBind();

但是，如果您有多个字段，那么您可以这样做：

        DataTable dtTable = new DataTable();

        try
        {
            using (SqlConnection sqlConnection = new SqlConnection("Your connection"))
            {
                using (SqlCommand sqlCommand = new SqlCommand("Select Item, id FROM Calendar Where UserD='Test'", sqlConnection))
                {
                    sqlConnection.Open();

                    using (SqlDataReader sqlDataReader = sqlCommand.ExecuteReader())
                    {
                        dtTable.Load(sqlDataReader);
                        sqlDataReader.Close();
                    }
                }
            }
        }
        catch (Exception error)
        {
            throw error;
        }

        ddlList.DataSource = dtTable;
        ddlList.DataValueField = "id";
        ddlList.DataTextField = "item";
        ddlList.DataBind();

Answer 3

添加此行方式

ddlList.DataSource = sqlTa;
ddlList.DataValueField = "ValueFieldFromDatabaseResults";
ddlList.DataTextField = "ShownTextFieldFromDatabaseResults";
ddlList.DataBind();

然后你错过了连接字符串

SqlConnection myConn="must add your connection string code here "

你还没有打开连接字符串所以

添加myconn.open()

为了

 SqlConnection myConn="must add your connection string code here "
`myconn.open()`
 SqlDataAdapter sqlDa = new SqlDataAdapter(strQuery,myConn)

Answer 4

试试这个..

 ddlList.DataSource = sqlTa;                 
 ddlList.DataTextField = "class";
 ddlList.DataBind();

添加ddList.Value="somefield"是可选的