Blog
Mert Özen's blog posts on software development, backend, frontend, and DevOps.
Multi-Mapping and splitOn in Dapper: Reading Related Data in a Single Query
We see how Dapper's multi-mapping cuts rows into column slices, the default splitOn = "Id" error, custom and comma-separated splitOn, the dictionary pattern for 1-N and null behavior on a LEFT JOIN, and we measure and fix the N+1 problem with a JOIN and IN @ids.
Transactions with Dapper: BeginTransaction, Commit, Rollback and TransactionScope
Starting from a half-written order, we set up BeginTransaction, the transaction: parameter, commit and rollback-on-dispose in Dapper, and see with real output why forgetting the parameter stays silent on SQLite, how isolation levels behave, and the async and SQLite traps of TransactionScope.
Async and Connection Management in Dapper: CancellationToken, Pooling and DI
We see with real output why a CancellationToken only travels through CommandDefinition in Dapper, why async on SQLite actually runs synchronously, how connection pooling helps, why sharing one connection breaks, and the connection factory pattern in ASP.NET Core.
INSERT, UPDATE, DELETE with Dapper Execute: Affected Rows and the New Id
We run INSERT, UPDATE and DELETE with Execute and read the affected row count, get the new id with RETURNING and last_insert_rowid(), look at SQL Server OUTPUT and PostgreSQL RETURNING, and measure why Execute with a list is not bulk.
Parameters and SQL Injection with Dapper: The Rules of a Safe Query
We see with a real attack why string concatenation opens the door to SQL injection, then look at anonymous objects, DynamicParameters, IN @Ids list expansion, DbString and the $ prefix, along with silent traps such as ORDER BY @Column.
Single-Row Queries with Dapper: QueryFirst, QuerySingle and ExecuteScalar
We run QueryFirst, QueryFirstOrDefault, QuerySingle and QuerySingleOrDefault side by side with zero, one and many rows to see which exception each throws and when, along with the pitfalls of default(T), nullable types and ExecuteScalar<T>.
Query and Mapping with Dapper: How Do Columns Map to Properties?
We look at how Query<T> maps columns to properties: case-insensitive matching, silently skipped columns, NULL and default values, MatchNamesWithUnderscores and its cache trap, dynamic results and constructor mapping for records.
What Is Dapper? The Thin Layer on Top of ADO.NET and Your First Query
We meet Dapper as a set of extension methods on top of ADO.NET: what micro-ORM means, when to pick it over EF Core, setting up .NET 10 + Dapper 2.1.89 + SQLite, the first Query and a short history from 1.x to Dapper.AOT.
What's New in EF Core 10: Named Query Filters, LeftJoin and Complex Types in JSON
Named query filters and IgnoreQueryFilters(["..."]), LeftJoin/RightJoin, ExecuteUpdateAsync with a regular lambda, complex types and ComplexCollection mapped to JSON, padded parameterized collections, vector search with SqlVector and the SQLite DateTimeOffset breaking change in EF Core 10 LTS.
What's New in EF Core 9: UseSeeding, Migration Locking and PendingModelChangesWarning
PendingModelChangesWarning catching a missing migration at Migrate time, the HasData and DateTime.Now trap, UseSeeding/UseAsyncSeeding, migration locking with __EFMigrationsLock, auto-discovered compiled models and EFOptimizeContext, and ExecuteUpdate with complex types in EF Core 9.
What's New in EF Core 8: Complex Types, Primitive Collections and SqlQuery<T>
Primitive collections and json_each, ComplexProperty for value objects, SqlQuery<T> for non-entity types, no-tracking lazy loading, JSON on SQLite and HierarchyId in EF Core 8 LTS, plus Contains moving to OPENJSON and UseCompatibilityLevel(120).
What's New in EF Core 7: ExecuteUpdate, ExecuteDelete, JSON Columns and TPC
ExecuteUpdate/ExecuteDelete, ToJson for owned types in JSON columns, TPC inheritance, IMaterializationInterceptor, FromSql and SqlQuery<int> in EF Core 7, plus moving from EF Core 6 with breaking changes like Encrypt=True and HasTrigger.