c# - C#判断记录是否存在

Question

我将数据插入到数据库中，如下所示:

var N_ID = " 001T ";
var N_Email = N_EmailAdd;
TourCenterDBEntities NewsLetterEntities = new TourCenterDBEntities();
News_Letter NewsLetterDetails = new News_Letter();
NewsLetterDetails.N_id = N_ID;
NewsLetterDetails.N_Email = N_Email;
NewsLetterEntities.News_Letter.Add(NewsLetterDetails);
NewsLetterEntities.SaveChanges();

记录正确保存到数据库，但在我插入之前，我想知道该记录是否存在。我该怎么做。

Answer 1

在你插入之前，你可以这样检查:

if(NewsLetterEntities.Any(entity => entity.N_id == N_ID)) {
   // Return or throw, your choice
}