c# - 如何使用引用单个主键的外键将多个图像插入到 MySQL 数据库表中

Question

我有一个包含两个表的 MYSQL 数据库，property 和 propertyImages，property 有一个主键(propertyID)，它与其他列一起自动递增，propertyImages 有一个外键，它是 propertyID。

当我向属性表中插入数据(如属性名称、位置等)时，用户选择的多个图像被插入到属性图像表中，外键与属性表中最后插入的主键相同。

当我插入数据时，属性表行正确填充没有问题，并且多个选定的第一张图像使用正确的外键输入到 propertyImages 表中，但随后它崩溃并且不保存其余图像或图片路径。

        string constr = ConfigurationManager.ConnectionStrings["realestatedbAddConString"].ConnectionString;




        using (MySqlConnection con = new MySqlConnection(constr))
        {
            using (MySqlCommand cmd = new MySqlCommand("INSERT INTO property (PropertyName, PropertyNumBeds, PropertyType, PropertyPrice, PropertyFeatures, PropertyLocation, PropertyInformation, ImageName, ImageMap) VALUES (@PropertyName, @PropertyNumBeds, @PropertyType, @PropertyPrice, @PropertyFeatures, @PropertyLocation, @PropertyInformation, @ImageName, @ImageMap)"))
            {
                using (MySqlDataAdapter sda = new MySqlDataAdapter())
                {
                    cmd.Parameters.AddWithValue("@PropertyName", PropertyName);
                    cmd.Parameters.AddWithValue("@PropertyNumBeds", PropertyNumBeds);
                    cmd.Parameters.AddWithValue("@PropertyPrice", PropertyPrice);
                    cmd.Parameters.AddWithValue("@PropertyType", PropertyType);
                    cmd.Parameters.AddWithValue("@PropertyFeatures", PropertyFeatures);
                    cmd.Parameters.AddWithValue("@PropertyLocation", PropertyLocation);
                    cmd.Parameters.AddWithValue("@PropertyInformation", PropertyInformation);


                    string FileName = Path.GetFileName(MainImageUploada.FileName);
                    MainImageUploada.SaveAs(Server.MapPath("ImagesUploaded/") + FileName);


                    cmd.Parameters.AddWithValue("@ImageName", FileName);
                    cmd.Parameters.AddWithValue("@ImageMap", "ImagesUploaded/" + FileName);


                    cmd.Connection = con;
                    con.Open();
                    cmd.ExecuteNonQuery();
                    con.Close();
                }
            }
        }


        if (ImageUploada.HasFiles)
        {
            foreach(var file in ImageUploada.PostedFiles)
            {
                string FileName = Path.GetFileName(ImageUploada.FileName);
                ImageUploada.SaveAs(Server.MapPath("ImagesUploaded/") + file.FileName);

                using (MySqlConnection con = new MySqlConnection(constr))
                {
                    using (MySqlCommand cmd = new MySqlCommand("INSERT INTO propertyimage(MultipleImageName, MultipleImageMap, PropertyID) VALUES (@MultipleImageName, @MultipleImageMap, LAST_INSERT_ID()); "))
                    {


                        using (MySqlDataAdapter sda = new MySqlDataAdapter())
                        {

                            cmd.Parameters.AddWithValue("@MultipleImageName", file.FileName);
                            cmd.Parameters.AddWithValue("@MultipleImageMap", "ImagesUploaded/" + file.FileName);

                            cmd.Connection = con;
                            con.Open();
                            cmd.ExecuteNonQuery();
                            con.Close();
                        }
                    }
                }

            }
        }


        txtName.Text = "";
        txtPropFeat.Text = "";
        txtPropInfo.Text = "";
        txtPropLoc.Text = "";
        txtNumBeds.Text = "";
        txtPrice.Text = "";
        txtPropType.Text = "";

        Label1.Visible = true;
        Label1.Text = "Property Added to Database Successfully!";

    }

这是错误信息: MySql.Data.dll 中出现类型为“MySql.Data.MySqlClient.MySqlException”的异常，但未在用户代码中处理

Additional information: Cannot add or update a child row: a foreign key constraint fails (realestatedb.propertyimage, CONSTRAINT propertyimage_ibfk_1 FOREIGN KEY (PropertyID) REFERENCES property (PropertyID) ON DELETE CASCADE ON UPDATE CASCADE)

编辑:有类似问题的人的工作示例

string PropertyName = txtName.Text;
            string PropertyFeatures = txtPropFeat.Text;
            string PropertyLocation = txtPropLoc.Text;
            string PropertyInformation = txtPropInfo.Text;
            string PropertyNumBeds = txtNumBeds.Text;
            string PropertyPrice = txtPrice.Text;
            string PropertyType = txtPropType.Text;
            long InsertedID;

            string constr = ConfigurationManager.ConnectionStrings["realestatedbAddConString"].ConnectionString;

            using (MySqlConnection con = new MySqlConnection(constr))
            {
                using (MySqlCommand cmd = new MySqlCommand("INSERT INTO property (PropertyName, PropertyNumBeds, PropertyType, PropertyPrice, PropertyFeatures, PropertyLocation, PropertyInformation, ImageName, ImageMap) VALUES (@PropertyName, @PropertyNumBeds, @PropertyType, @PropertyPrice, @PropertyFeatures, @PropertyLocation, @PropertyInformation, @ImageName, @ImageMap)"))
                {
                    using (MySqlDataAdapter sda = new MySqlDataAdapter())
                    {
                        cmd.Parameters.AddWithValue("@PropertyName", PropertyName);
                        cmd.Parameters.AddWithValue("@PropertyNumBeds", PropertyNumBeds);
                        cmd.Parameters.AddWithValue("@PropertyPrice", PropertyPrice);
                        cmd.Parameters.AddWithValue("@PropertyType", PropertyType);
                        cmd.Parameters.AddWithValue("@PropertyFeatures", PropertyFeatures);
                        cmd.Parameters.AddWithValue("@PropertyLocation", PropertyLocation);
                        cmd.Parameters.AddWithValue("@PropertyInformation", PropertyInformation);


                        string FileName = Path.GetFileName(MainImageUploada.FileName);
                        MainImageUploada.SaveAs(Server.MapPath("ImagesUploaded/") + FileName);


                        cmd.Parameters.AddWithValue("@ImageName", FileName);
                        cmd.Parameters.AddWithValue("@ImageMap", "ImagesUploaded/" + FileName);


                        cmd.Connection = con;
                        con.Open();
                        cmd.ExecuteNonQuery();
                        InsertedID = cmd.LastInsertedId;
                        con.Close();
                    }
                }
            }



            if (ImageUploada.HasFiles)
            {
                foreach(var file in ImageUploada.PostedFiles)
                {
                    string FileName = Path.GetFileName(ImageUploada.FileName);
                    ImageUploada.SaveAs(Server.MapPath("ImagesUploaded/") + file.FileName);


                    using (MySqlConnection con = new MySqlConnection(constr))
                    {
                        using (MySqlCommand cmd = new MySqlCommand("INSERT INTO propertyimage(MultipleImageName, MultipleImageMap, PropertyID) VALUES (@MultipleImageName, @MultipleImageMap, @InsertedID); "))
                        {
                            using (MySqlDataAdapter sda = new MySqlDataAdapter())
                            {
                                cmd.Parameters.AddWithValue("@MultipleImageName", file.FileName);
                                cmd.Parameters.AddWithValue("@MultipleImageMap", "ImagesUploaded/" + file.FileName);
                                cmd.Parameters.AddWithValue("@InsertedID", InsertedID);

                                cmd.Connection = con;
                                con.Open(); 
                                cmd.ExecuteNonQuery();
                                con.Close();
                            }
                        }
                    }

                }
            }

Answer 1

你的问题是这一行:

using (MySqlCommand cmd = new MySqlCommand("INSERT INTO propertyimage(MultipleImageName, MultipleImageMap, PropertyID) VALUES (@MultipleImageName, @MultipleImageMap, LAST_INSERT_ID()); "))

这将在第一次插入时起作用，因为 LAST_INSERT_ID 是适当的外键值。

但是在第二个 插入时，LAST_INSERT_ID 现在已更改为您刚刚插入的记录(第一个插入)的 ID 值。

要解决此问题，您需要获取 LAST_INSERT_ID into a C# variable , 然后将其传递到每个后续 SQL 语句中(即 @ForeignKeyID 而不是 LAST_INSERT_ID)。

这意味着改变您的第一:

cmd.ExecuteNonQuery();

到:

cmd.ExecuteNonQuery();
insertedID = cmd.LastInsertedId;

其中 insertedID 是您在方法顶部声明的变量(可能是 int)。

然后您需要更改:

using (MySqlCommand cmd = new MySqlCommand("INSERT INTO propertyimage(MultipleImageName, MultipleImageMap, PropertyID) VALUES (@MultipleImageName, @MultipleImageMap, LAST_INSERT_ID()); "))
{


    using (MySqlDataAdapter sda = new MySqlDataAdapter())
    {

        cmd.Parameters.AddWithValue("@MultipleImageName", file.FileName);
        cmd.Parameters.AddWithValue("@MultipleImageMap", "ImagesUploaded/" + file.FileName);

        cmd.Connection = con;
        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
    }
}

到:

using (MySqlCommand cmd = new MySqlCommand("INSERT INTO propertyimage(MultipleImageName, MultipleImageMap, PropertyID) VALUES (@MultipleImageName, @MultipleImageMap, @InsertedID); "))
{


    using (MySqlDataAdapter sda = new MySqlDataAdapter())
    {

        cmd.Parameters.AddWithValue("@MultipleImageName", file.FileName);
        cmd.Parameters.AddWithValue("@MultipleImageMap", "ImagesUploaded/" + file.FileName);
        cmd.Parameters.AddWithValue("@MultipleImageMap", "ImagesUploaded/" + file.FileName);
        cmd.Parameters.AddWithValue("@InsertedID", InsertedID);

        cmd.Connection = con;
        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
    }
}