dapper

Dapper is a NuGet library for .NET that enhances ADO.NET connections through extension methods on DbConnection. It provides a simple, efficient API for invoking SQL, supporting both synchronous and asynchronous data access, and both buffered and non-buffered queries. Key APIs include Execute for insert/update/delete operations, Query for multi-row queries, and QuerySingle for single-row queries. Parameters can be passed as simple POCOs, anonymous types, dictionaries, or DynamicParameters instances. The library maps query results to typed objects or dynamic lists, supports executing commands multiple times for bulk operations, and handles parameterized queries with named parameters. It also supports list expansion for IN clauses, literal replacements for bool and numeric types, and buffered versus unbuffered readers. Additional features include multi-mapping to split a single row into multiple objects, processing multiple result grids in one query, stored procedure support with output and return value parameters, ANSI string handling for varchar columns, and per-row type switching via IDataReader.GetRowParser. Dapper was originally developed for and by Stack Overflow and remains free and open source. The repository includes several related packages: Dapper.EntityFramework for Entity Framework extension handlers, Dapper.Rainbow as a micro-ORM with CRUD helpers, Dapper.SqlBuilder for dynamic SQL query building, and StrongName variants. The README also documents performance benchmarks comparing Dapper against other ORMs and hand-coded data access.