Question

我正在尝试从SQL查询创建一个linq表达式。

我最大的问题是创建这一行：

CASE WHEN MIN() <> MAX() THEN 1 ELSE 0

在Linq表达式中。

SQL查询工作正常：

SELECT 
    CLD.Id, CLD.Comments,
    CASE 
       WHEN MIN(AnswerComment.IdStatus) <> MAX(AnswerComment.IdStatus) 
       THEN 1 ELSE 0
    END AS statusDifference
FROM 
    CLD 
INNER JOIN 
    AnswerComment on CLD.Id = AnswerComment.IdCLD
INNER JOIN 
    ListDef on CLD.IdListDef = ListDef.Id
WHERE 
    ListDef.IdInspection = 1042
GROUP BY 
    CLD.Id, CLD.Comments

我正在尝试将此SQL查询转换为C＃上的Linq表达式。

var sql = (from CLD in db.CLD
                       join AnswerComment in db.AnswerComment
                           on CLD.Id equals AnswerComment.IdCLD
                       join ListDef in db.ListDef
                           on CLD.IdListDef equals ListDef.Id
                       where ListDef.IdInspection == idInspec
                       group CLD by new ComentRespostaLFDModels
                       {
                           IdComment = CLD.Id,
                           Comment = CLD.Comments
                       } into coments
                       select new ComentRespostaLFDModels
                       {
                           IdComment = coments.Key.IdComment,
                           Comment = coments.Key.Comment
                           * Here I need to do the case: "CASE WHEN MIN(AnswerComment.IdStatus) <> MAX(AnswerComment.IdStatus) THEN 1 ELSE 0" or in other place that I don't know
                       }).ToList();

Answer 1

您可以更改

之类的组子句

var sql = (from CLD in db.CLD
           join AnswerComment in db.AnswerComment on CLD.Id equals AnswerComment.IdCLD
           join ListDef in db.ListDef on CLD.IdListDef equals ListDef.Id
           where ListDef.IdInspection == idInspec
           group new { CLD, AnswerComment } by new ComentRespostaLFDModels
           {
               IdComment = CLD.Id,
               Comment = CLD.Comments
           } into coments
           select new ComentRespostaLFDModels
           {
               IdComment = coments.Key.IdComment,
               Comment = coments.Key.Comment,
               StatusDifference = comments.Min(c=>c.AnswerComment.IdStatus) != comments.Max(c=>c.AnswerComment.IdStatus) ? 1 : 0
           }).ToList();

Answer 2

 var sql = (from CLD in db.CLD
                   join AnswerComment in db.AnswerComment
                       on CLD.Id equals AnswerComment.IdCLD
                   join ListDef in db.ListDef
                       on CLD.IdListDef equals ListDef.Id
                   where ListDef.IdInspection == idInspec
                   group new {CLD = CLD, AnswerComment = AnswerComment } by new ComentRespostaLFDModels
                   {
                       IdComment = CLD.Id,
                       Comment = CLD.Comments
                   } into coments
                   select new ComentRespostaLFDModels
                   {
                       IdComment = coments.Key.IdComment,
                       Comment = coments.Key.Comment,
                       StatusDifference = coment.Min(c => c.AnswerComent.IdStatus) != coment.Max(c => c.AnswerComent.IdStatus) //if you want to return bool or coment.Min() != coment.Max() ? 1 : 0 if you want to return int
                   }).ToList();

Answer 3

试一试：

//Get all the ListDefIds where IdInspection == 1042
var listDefIds = db.ListDef.Where(x => x.IdInspection == 1042).Select(x => x.Id).ToList();

//filter CLD list by those ListDefId's
var filteredCLDList = db.CLD.Where(x => listDefIds.Contains(x.IdListDef)).ToList();

//filter answercomments by those whose IdCLD's are in the filtered CLD list
var filteredAnswerComments = db.AnswerComment.Where(x => filteredCLDList.Select(x => x.Id).Contains(x.IdCLD)).ToList();

//assuming status diff will always be same, calculate statusDiff
var statusDiff = filteredAnswerComments.Min(x.IdStatus) == filteredAnswerComments.Max(x.IdStatus) ? 0 : 1;

//filter CLD list again by filtered answercomments, then select new objects
var sql = filteredCLDList.Where(x => filteredAnswerComments.Select(x => x.IdCLD).Contains(x.Id))
            .Select(x => new { Id = x.Id, Comments = x.Comments, statusDifference = statusDiff}).GroupBy(x => x.Id).ThenBy(x => x.Comments);

Linq表达式：在Linq表达式

3 个答案: