如何在 C# 中实现 dapper 使用的类

Question

I have just one simple question, it is how to create classes for these tables from the database, these classes are going to be used by dapper, any type of implementation works, weather it be your personnel or industry standard, just enough that a scarcely experienced new developer can perform crud operations with it

(it is not a question of experimenting because the start line is i do not know how to do these and there is absolutely no source explaining what i need and i have been scouring through the internet, believe it or not for a month, i am thankful for you concern about me just trying it out and searching, but i must respectfully decline no offense intended, i just want to crud, i hope this will not take much of you time

 public class mem                                     (main table to which every table connects)
{
public int Mem_id {get;set;}
public string Mem_name {get;set;}
public string Mem_gndr {get;set;}
public DateTime Mem_dob {get;set;}
//public int adrs_adrs_id {get;set;}
//public int union_union_id {get;set;}
//public int alot_alot_id {get;set;}
}

public class adrs                            (one to one mandatory relationship with mem table)
{
public int adrs_id {get;set;}
public string adrs_col1 {get;set;}
public string adrs_col2 {get;set;}
}


public class alot                        (one to one optional relationship with mem table)
{
public int alot_id {get;set;}
public string alot_no {get;set;}
}

public class union                           (one to many mandatory relationship with mem table)
{
public int union_id {get;set;}
public string union_nm {get;set;}
}



 public class ci                       (one to many optional relationship with mem table)
{
public int ci_id {get;set;}
public string ci_mob {get;set;}
public string ci_eml {get;set;}
//public int mem_Mem_id {get;set;}
}

 public class flat                                  (many to many relationship with mem table)
{
public int flat_id {get;set;}
public string flat_type {get;set;}
}

   public class mem_has_flat                      (this is the bridge class between mem and flat)
  {                                                (many to many relationship bridge)
    //public int mem_Mem_id {get;set;}
    //public int flat_flat_id {get;set;}
  }

)

I have written the code, properly formatted it, you must have understood where i am having problem with, it is the connecting properties, the commented out ones are the problem with the double forward slash

THIS TOOK ME LOT OF TIME TO WRITE PLEASE HELP, I KNOW BEGGING REMOVES THE QUESTION, BUT I JUST WANT TO SHOW THAT I HAVE DONE MY RESEARCH, EXPLAINED THAT TO THE BEST OF MY ABBILITIES, LET THIS STAY AS IS DO NOT EDIT IT OUT, HUMBLE REQUEST

i mean no disrespect i am just badly stuck without time

Answer 1

The easiest way to use Dapper is not to try to map one-to-one with the tables. Instead, build business domain entities that map to your queries. I can't quite understand your schema (is mem a member or is it something about memory).

Instead, consider a classic order system with three tables: Customer, Order and Order_Item.

Customer
    Customer_Id int,
    Customer_Name varchar(50)
    -- etc 

Order 
    Order_Id int,
    Customer_Id int,
    Order_Date DateTime,
    -- etc

Order_Item
    Order_Item_Id int,
    Order_Id int,
    Item_Name varchar (50),
    Item_Description varchar(500),
    Item_Sold_Price decimal(12, 2),
    Item_Quantity int,
    --etc

I left out nullability, index and FK information from that description.

Now consider that you want to show your users a list of the last 10 things they bought, showing the date of purchase

SELECT TOP (10)
    o.OrderDate as PurchasedDate,
    oi.Item_Name as Item,
    oi.Item_Description as Description, 
    oi.Item_Quantity as Quantity, 
    oi.Item_Sold_Price as Price
FROM Order_Item oi
INNER JOIN Order o ON o.Order_Id = oi.Order_Id
INNER JOIN Customer c ON c.Customer_Id = o.Customer_Id
WHERE c.Customer_Id = @Customer_Id

With that query I'd prepare a class that looks like

public class CustomerOrderItems {
    public DateTime PurchasedDate { get; set; }
    public string Item { get; set; }
    public string Description { get; set; }
    public int Quantity { get; set; }
    public decimal Price { get; set; }
}

Note that the member names and types match the column names and types of the result set from the query. Now, assuming you have that query in a string variable named query and a customer ID in a variable named customerId , you could get the results with

var results = sqlConn.Query<CustomerOrderItems>(query, new {Customer_Id = customerId});

After that, results would contain an IEnumerable<CustomerOrderItems> containing up to ten results.