c# - Linq使用案例

Question

我想在 TableType 上应用条件。

If t.TableName='limit' then TabeType should be A_TypeTable
If t.TableName='health' then TabeType should be B_TypePolicy
If t.TableName='waiting' then TabeType should be C_TypeTable

下面是查询。我不确定在哪里分配 case 语句。

 var query = from a in tableA
                        join b in tableB on a.Hid equals b.Hid into ab
                        select new
                        {

                            TableType= ab.Select(t=>t.TableName).FirstOrDefault(),
                            UserName = a.UserName,
                            Description = a.Description,
                            ImportedDate =   a.ImportedDate

                        };

如有任何建议，我们将不胜感激。提前致谢

Answer 1

像这样尝试使用三元运算符将条件转换为 SQL 中的 CASE。

var query = from a in tableA
                                join b in tableB on a.Hid equals b.Hid into ab
                                let x= ab.Select(t => t.TableName).FirstOrDefault()
                                select new
                                {

                                    TableType = x.equal("limit")? "A_TypeTable" : 
                                                x.equal("health") ? "B_TypeTable":
                                                "C_TypeTable",
                                    UserName = a.UserName,
                                    Description = a.Description,
                                    ImportedDate = a.ImportedDate

                                };