The main difference between foreach and LINQ is that foreach is used for simple iteration, while LINQ is used for querying and manipulating data. LINQ queries are more expressive and can be used to perform complex operations on collections, such as filtering, sorting, and projecting data.

Are there any cases where LINQ query cannot replace foreach?

My point is that foreach is a typical statement implementing iteration against all entities fetched from the selected data source. The data source must implement IEnumerable. the from .. in.. clause is an expression that:

1. can be translated to a query
2. can be sent to the data source, and executed by the data source
3. can preselect a data sequence that will finally be the subject of further processing

The main consequence is that foreach requires all data to be fetched from the data source to the in-process memory, causing an overload.