First, I thought .FirstOrDefault() would return a NULL value if no records/sequences were not found. I ran the below code and after I get past the .Any(), I am changing the value in the database where the x.ITEM_NM would not be found etc. ...
每个FileInfo的实际状态可能会在开始和结束执行查询期间发生更改。 例如,可以创建FileInfo对象的列表来用作数据源。 如果尝试通过查询访问Length属性,则FileInfo对象会尝试访问文件系统来更新Length的值。 如果该文件不再存在,则会在查询中收到FileNotFoundException,即使未直接查询文件系统也是如此。
每个FileInfo的实际状态可能会在开始和结束执行查询期间发生更改。 例如,可以创建FileInfo对象的列表来用作数据源。 如果尝试通过查询访问Length属性,则FileInfo对象会尝试访问文件系统来更新Length的值。 如果该文件不再存在,则会在查询中收到FileNotFoundException,即使未直接查询文件系统也...
Occurs when the server control is initialized, which is the first step in its lifecycle. (Inherited from Control) Inserted Occurs when an insert operation has finished. Inserting Occurs before an insert operation. Load Occurs when the server control is loaded into the Page object. (Inherited ...
// The first argument is an expression that creates a new object of the specified type. Expression callExpr = Expression.Call( Expression.New(typeof(SampleClass)), typeof(SampleClass).GetMethod("AddIntegers", new Type[] { typeof(int), typeof(int) }), Expression.Constant(1), Expression....
publicstaticTSource? FirstOrDefault<TSource> (thisSystem.Linq.IQueryable<TSource> source); 类型参数 TSource source的元素类型。 参数 source IQueryable<TSource> 要返回其第一个元素的IQueryable<T>。 返回 TSource 如果source为空,则为default(TSource);否则为source中的第一个元素。
.First()' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync Really don't want to take Transactions into memory as is suggeste...
This method returnsnullif the element with the specified name is not found. All of the methods that allow you to construct elements (the constructor ofXElement,Add, and so on) acceptnullas a valid argument. This allows you to use a convenient idiom: you can call this method as part of ...
FirstOrDefault(); // connection opened here var scope = new TransactionScope(); // this transaction was not attached to connection // because it was opened earlier product.Name = "Lollipop"; db.Update(product); scope.Dispose(); // no transaction rollback happed, "Lollipop" has been saved...
LanguageRepository.GetProgrammingLanguages();/* LINQ extension methods */// The extension methods extend any Type that implements the IEnumerable interface/* The First() extension method:- Returns the first element of the sequence- The First() method will throw an exception if no match is found...