c#将SQL语句转换为lambda表达式

本文关键字：lambda 表达式 转换 语句 SQL | 更新日期: 2023-09-27 18:16:53

我有这样的SQL语句:

 SELECT questionNo , ActivityID ,GROUP_CONCAT(CONCAT(Question, '[' , Answer , ']')
 SEPARATOR ' ')AS joined
 FROM question
 GROUP BY QuestionNo , ActivityID
 LIMIT 0,30

但我使用实体框架MySQL和我的大多数类文件方法是lambda，我如何将其转换为lambda表达式?

下面 -------------

public IList<Model.question> GetList()
    {
        IList<Model.question> lstRecords = context.questions.ToList();
        return lstRecords.GroupBy(x => new { x.QuestionNo, x.ActivityID }).Select(g => new { QuestionNo = g.Key.QuestionNo, ActivityID = g.Key.ActivityID, joined = string.Join(" ", g.Select(i => i.QuestionContent + "[" + i.Answer + "]"))});
    }

如果我想获得它的列表，我应该如何写它?它说不能将ienumerable类型转换为ilist

c#将SQL语句转换为lambda表达式

try below 

var result = question.GroupBy(x=>new{x.QuestionNo , x.ActivityID})
.Select(g=> new {QuestionNo= g.Key.QuestionNo, 
                 ActivityID= g.Key.ActivityID,
                 joined = string.Join(" ", g.Select(i=>i.Question+ "[" + i.Answer +"]"))})
.Take(30);

如果你想从方法中返回这个，你可以像下面这样创建一个新类

public class Question
{
    public int QuestionNo {get;set;} //change the type accordingly 
    public string ActivityID {get;set;} //change the type accordingly 
    public string joined {get;set;}   //change the type accordingly 
}

并将方法更改为:

public IList<Question> GetList()
{
    IList<Question> lstRecords = context.questions.GroupBy(x => new { x.QuestionNo, x.ActivityID })
        .Select(g => new Question(){
              QuestionNo = g.Key.QuestionNo, 
              ActivityID = g.Key.ActivityID, 
              joined = string.Join(" ", 
                     g.Select(i => i.QuestionContent + "[" + i.Answer + "]"))})
       .Take(30)
       .ToList();
}
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