Linq查詢類型推斷在對Join的調用中失敗

Question

我已經查看了各種stackoverflow的答案，但我沒有看到修復我與linq的連接的方法。

2桌

var query = from tips in TblTips
            where tips.Id == 30
            join files in TblFiles on tips.Id equals files.Group
            select new { tips, files };

錯誤：

Type inference failed in the call to Join

現在tips.Id是一個int而files.Group是一個varchar

我試過做.Value

tips.id.Value       -->  the word Value not working  (most recent linqpad)

(int)files.Group    -->  it doesn't like that ... 

Answer 1

問題是你不能連接不同類型的表列值！

Convert.ToInt32(column)  should work in linqpad and your c# application just fine.

（我用parens包裹並添加了一個ToList（））

如果group是string並且id是int，這應該適合你

var query = (from tips in TblTips
            where tips.Id == 30
            join files in TblFiles on tips.Id equals Convert.ToInt32(files.Group)
            select new { tips, files }).ToList();

更新：

每個OP，我同意他，因為它應該將其他值轉換為字符串

var query = (from tips in TblTips
            where tips.Id == 30
            join files in TblFiles on tips.Id.ToString() equals files.Group
            select new { tips, files }).ToList();