如何连接两个表并从中获取数据

Question

我有两个表，我想从中获取数据并将其返回给 API 以供使用。两个表之间是有关系的。

[![在此处输入图片描述][1]][1]

当我尝试获取数据时，它只返回一行，这不是我想要的。

如何返回与ResellerId 相关的所有数据（8435 个示例）？

这是我的代码：

    public RateSheetModel GetRateSheet(int resellerId)
    {
        // This only returns only one row.
        // How can I get all rows for all the same Id?
        var rateSheetDetails = (from r in _Context.WholesaleRateSheet 
                                where r.ResellerId == resellerId 
                                select r).First();
    }   

模型

public class WholesaleRateSheetMarkup
{
    [Key]
    public int RateSheetMarkupId { get; set; }
    [Required]
    public int ResellerId { get; set; }
    [StringLength(50)]
    public string RatesheetName { get; set; }

} 

public class WholesaleRateSheet
{
    [Key]
    public int RateSheetId { get; set; }
    [Required]
    public int RateSheetMarkupId { get; set; }
    [Required]
    public int ResellerId { get; set; }
    public string CountryCode { get; set; }
    public string Description { get; set; }
    public decimal Peak { get; set; }
    public bool IsSouthAfricanRate { get; set; }
    public bool IsInertnationRate { get; set; }
    public bool IsSpecificRate { get; set; }
    public int DestinationGroupSetId { get; set; }
    public int DestinationGroupId { get; set; }
    public string DestinationLookup { get; set; }
    public DateTime CreatedDate { get; set; }
    public string CreatedByUsername { get; set; }
    public DateTime LastUpdatedDate { get; set; }
    public string UpdatedByUsername { get; set; }

}  

Answer 1

    var rateSheetDetails = (from r in _Context.WholesaleRateSheet 
                            join rateSheet in _Context.<tableName> on r.ResellerId equals rateSheet.ResellerId
                            where r.ResellerId == resellerId 
                            select new { foo });

您这样做是在创建一个新类型，作为两个表中数据的组合。您可以定义一个模型类并使用类似的东西

select new MyClass {
  Foo = r.RateSheetMarkupId,
  Bar = rateSheet.RateSheetName
}

否则，不需要类定义。简单地使用不带类的“新”将创建一个匿名类型，其属性与您选择的内容相匹配。如果您共享实体名称，此处的示例可能会更精确。

总而言之，关闭你的代码：

    public List<RateSheetModel> GetRateSheet(int resellerId)
    {
        var rateSheetDetails = (from r in _Context.WholesaleRateSheet
                                join m in _Context.RateSheetMarkup on r.ResellerId equals m.ResellerId
                                where r.ResellerId == resellerId 
                                select new RateSheetModel  {
                                    ResellerId = r.ResellerId
                                    RatesheetName = m.RatesheetName
                                };
        return rateSheetDetails.ToList<RateSheetModel>;


    }
    
public RateSheetModel  { //dunno what this model looks like, but example
   public int ResellerId {get; set;}
   public string RatesheetName {get; set;}
}