Question

我正在使用dapper，并且尝试使用以下教程将列表插入数据库。

https://dapper-tutorial.net/knowledge-base/17150542/how-to-insert-a-csharp-list-to-database-using-dapper-net

我首先从此示例中认为，这意味着@A @B必须在我的班级中，但从该示例中并不明显它们必须在我的班级中。

public void ExportTOSql()
{
   string connectionString;
   connectionString = System.Configuration.ConfigurationManager.
   ConnectionStrings["Dapper"].ConnectionString.ToString();
     _salesOrders = Program.SageDatabaseHelper.FetchSoPOrdersODBC().OrderByDescending(o => o.OrderDate).ToList();

 using (SqlConnection conn = new SqlConnection(connectionString))
 {
     conn.Open();              
     string processQuery = "INSERT INTO SalesOrders VALUES (@OrderDate, @OrderNumber, @DespatchDate,@AccountReference,@CustomerOrderNumber,@Name,@TotalAmount,@Allocated,@Despatched,@Printed)"; 
     conn.Execute(processQuery, _salesOrders);

}

我的销售订单类如下，您可以看到OrderDate在这里。

public class SalesOrder
{
    public DateTime OrderDate;
    public int OrderNumber;
    public byte OrderType;
    public string DespatchDate;
    public string AccountReference;
    public string CustomerOrderNumber;
    public string Name;
    public double TotalAmount;
    public string Allocated;
    public string Despatched;
    public bool Printed;
}

但是从屏幕截图中可以看到，这是我收到的消息：

编辑2 OK：由于帮助我提高了对这一点的了解，我已经迈出了一步。现在的结构是：

public class SalesOrder
{
    public int OrderNumber { get; set; }
    public DateTime OrderDate { get; set; }   
    public byte OrderType { get; set; }
    public DateTime DespatchDate { get; set; }
    public string AccountReference { get; set; }
    public string CustomerOrderNumber { get; set; }
    public string Name { get; set; }
    public double TotalAmount { get; set; }
    public string Allocated { get; set; }
    public string Despatched { get; set; }
    public bool Printed { get; set; }
}

我的导出方法如下：

public void ExportTOSql()
{
        string connectionString;
        connectionString = System.Configuration.ConfigurationManager.
ConnectionStrings["Dapper"].ConnectionString.ToString();
        _salesOrders = Program.SageDatabaseHelper.FetchSoPOrdersODBC().OrderByDescending(o => o.OrderDate).ToList();
        using (SqlConnection conn = new SqlConnection(connectionString))
        {
            conn.Open();
            string processQuery = "INSERT INTO SalesOrders VALUES ( @OrderNumber,@OrderDate,@OrderType , @DespatchDate,@AccountReference,@CustomerOrderNumber,@Name,@TotalAmount,@Allocated,@Despatched,@Printed)";
            conn.Execute(processQuery, _salesOrders);

}

我的sql表如下，但是现在我得到了以下内容：

System.Data.SqlClient.SqlException：“将数据类型nvarchar转换为数字时出错。”

所以这里的问题是它仍然无法将数据发送到SQL表。

Answer 1

这是因为您在模型中使用fields而不是properties。尝试将{get;set;}添加到每个字段中以使其成为属性。

public class SalesOrder
{
    public DateTime OrderDate { get; set; }
    public int OrderNumber { get; set; }
    public byte OrderType { get; set; }
    public string DespatchDate { get; set; }
    public string AccountReference { get; set; }
    public string CustomerOrderNumber { get; set; }
    public string Name { get; set; }
    public double TotalAmount { get; set; }
    public string Allocated { get; set; }
    public string Despatched { get; set; }
    public bool Printed { get; set; }
}

根据您提供的文档：

请注意，MyObject 属性名称 A和B与SQL参数名称@A和@B匹配。

完成此操作后，@OrderDate可以映射回模型的property OrderDate。

Answer 2

这是因为您没有正确使用查询参数化。从以下示例开始：

private static void UpdateDemographics(Int32 customerID,
string demoXml, string connectionString)
{
    string commandText = "UPDATE Sales.Store SET Demographics = @demographics "
        + "WHERE CustomerID = @ID;";

    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        SqlCommand command = new SqlCommand(commandText, connection);

        // You have to define the parameters, and give the input which it
        // gets value from. This will be put into the query that the 
        // framework produces
        command.Parameters.Add("@ID", SqlDbType.Int);
        command.Parameters["@ID"].Value = customerID;

        // Use AddWithValue to assign Demographics.
        // SQL Server will implicitly convert strings into XML.
        command.Parameters.AddWithValue("@demographics", demoXml);

        try
        {
            connection.Open();
            Int32 rowsAffected = command.ExecuteNonQuery();
            Console.WriteLine("RowsAffected: {0}", rowsAffected);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

您可以阅读有关此主题的信息here

Dapper使用列表插入数据库

2 个答案: