我正在尝试使用 EF6 更新记录。首先找到记录,如果存在则更新。 这是我的代码:
var book = new Model.Book
{
BookNumber = _book.BookNumber,
BookName = _book.BookName,
BookTitle = _book.BookTitle,
};
using (var db = new MyContextDB())
{
var result = db.Books.SingleOrDefault(b => b.BookNumber == bookNumber);
if (result != null)
{
try
{
db.Books.Attach(book);
db.Entry(book).State = EntityState.Modified;
db.SaveChanges();
}
catch (Exception ex)
{
throw;
}
}
}
每次我尝试使用上述代码更新记录时,我都会收到此错误:
{System.Data.Entity.Infrastructure.DbUpdateConcurrencyException: Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries
最佳答案
您正在尝试更新记录(对我来说这意味着“更改现有记录的值并将其保存回来”)。因此,您需要检索对象、进行更改并保存它。
using (var db = new MyContextDB())
{
var result = db.Books.SingleOrDefault(b => b.BookNumber == bookNumber);
if (result != null)
{
result.SomeValue = "Some new value";
db.SaveChanges();
}
}
关于c# - 如何使用 Entity Framework 6 更新记录?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25894587/