从C#中的多个表中读取-如何? [英] Reading from multiple tables in C# - how?

问题描述

嗨.

我想这是一个非常简单的问题，但我确实找不到适合我需求的答案！

我在MySQL数据库中有2个表:

家庭
-FamilyId
-城市
-电话

成员
-FamilyId
-Birtdate

家庭ID当然是将成员绑定到家庭的主键.
所以我想要的是获取正确的家庭行，以及属于该家庭的所有成员行，如下所示:

Hi.

I guess this is a very simple question, but I really can''t find the answer that suits my needs!

What I have is 2 tables in a MySQL database:

Families
- FamilyId
- City
- Phone

Members
- FamilyId
- Birtdate

The family id is of course the primary key, that binds members to a family.
So what I want is to get the right family row, and all member rows that belongs to this family like this:

string Query="SELECT * FROM `Families`, `Members` WHERE `Families`.`FamilyId`=''123'' AND `Members`.`FamilyId`=''123'';";

但是，如何遍历结果，以便可以创建相应的系列对象以及C#应用程序中具有的相应Member对象?

But how do I iterate over the result, so that I can create the corresponding family object, and the corresponding Member objects that I have in my C# application?

MysqlConnection.Open();
MySqlCommand MysqlCommand=new MySqlCommand(Query,MysqlConnection);
MysqlReader=MysqlCommand.ExecuteReader();

while (MysqlReader.Read()) {
  //what should I do here?
}

非常感谢！

Thanks a lot!

推荐答案

在执行查询

"SELECT * FROM `Families`, `Members` WHERE `Families`.`FamilyId`='123' AND `Members`.`FamilyId`='123'"

将家庭和成员"表加入1个结果集中.

输出结果将是

You join the to tables Families and Members into 1 result set.

The output result will be

FamilyId,City,Phone,FamilyId,Birtdate

最后返回的每一行有5列.

在您的while循环中，您可以执行以下操作:

Ending up with 5 column on each row returned.

In your while loop you can then do:

while (reader.Read())
{
  FamiliesObject f = new FamiliesObject((int)reader[0], (string)reader[1], (string)reader[2]); // Column FamilyId, City, Phone
  MembersObject m = new MembersObject((int)reader[3], (DateTime)reader[4]); // Column FamilyId and Birtdate
}

您必须创建FamiliesObject和MembersObject类.而且FamiliesObject可能看起来像这样.

You have to create FamiliesObject and MembersObject class. And FamiliesObject could look like this.

public class FamiliesObject
{
  public int FamilyId;
  public string City;
  public string Phone;

  public FamiliesObject(int familyId, string city, string phone)
  {
    this.FamilyId = familyId;
    this.City = city;
    this.Phone = phone;
  }
}

希望您能理解:-)

Hope you get the idea :-)

在遍历过程中，读取5个值，并调用两个构造函数，每个构造函数分别取3个值，并将它们放在列表中，也许检查一下首先，他们还不存在.

Well, as you iterate through, read the 5 values, and call the two constructors taking 3 values each, and put them in a list, perhaps checking first that they are not there already.

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