LINQ
Querying collections, objects and databases from C#.
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This course has 3 lessons. Start with the first one and use the next / previous links at the bottom of each lesson — the sidebar keeps the whole course in order.
Lessons
- Query syntax and method syntaxThe two spellings of LINQ, how the compiler rewrites one into the other, and which to reach for in a given situation.
- Common LINQ operatorsFiltering, projection, ordering, aggregation and the element operators, with the traps that produce exceptions in production.
- Deferred execution and querying a databaseWhy a query does nothing until you enumerate it, the IEnumerable versus IQueryable divide, and how EF Core turns expressions into SQL.
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Last refreshed 2026-09-17.