Dapper Tutorial Dapper - Async
Description
Dapper also extend the IDbConnection interface with Async (asynchronous) methods:
- ExecuteAsync
- QueryAsync
- QueryFirstAsync
- QueryFirstOrDefaultAsync
- QuerySingleAsync
- QuerySingleOrDefaultAsync
- QueryMultipleAsync
We only added a non-asynchronous version in this tutorial to make it easier to read.
ExecuteAsync
The ExecuteAsync can execute a command one or multiple times asynchronously and return the number of affected rows.
string sql = "INSERT INTO Customers (CustomerName) Values (@CustomerName);"; using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools())) { var affectedRows = connection.ExecuteAsync(sql, new {CustomerName = "Mark"}).Result; Console.WriteLine(affectedRows); var customer = connection.Query<Customer>("Select * FROM CUSTOMERS WHERE CustomerName = 'Mark'").ToList(); FiddleHelper.WriteTable(customer); }
Try it: .NET Core | .NET Framework
QueryAsync
The QueryAsync can execute a query and map the result asynchronously.
string sql = "SELECT TOP 10 * FROM OrderDetails"; using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools())) { var orderDetails = connection.QueryAsync<OrderDetail>(sql).Result.ToList(); Console.WriteLine(orderDetails.Count()); FiddleHelper.WriteTable(orderDetails); }
Try it: .NET Core | .NET Framework
QueryFirstAsync
The QueryFirstAsync can execute a query and map asynchronously the first result.
string sql = "SELECT * FROM OrderDetails WHERE OrderDetailID = @OrderDetailID;"; using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools())) { var orderDetail = connection.QueryFirstAsync<OrderDetail>(sql, new {OrderDetailID = 1}).Result; FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } ); }
Try it: .NET Core | .NET Framework
QueryFirstOrDefaultAsync
The QueryFirstOrDefaultAsync can execute a query and map asynchronously the first result, or a default value if the sequence contains no elements.
string sql = "SELECT * FROM OrderDetails WHERE OrderDetailID = @OrderDetailID;"; using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools())) { var orderDetail = connection.QueryFirstOrDefaultAsync<OrderDetail>(sql, new {OrderDetailID = 1}).Result; FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } ); }
Try it: .NET Core | .NET Framework
QuerySingleAsync
The QuerySingleAsync can execute a query and map asynchronously the first result and throws an exception if there is not exactly one element in the sequence.
string sql = "SELECT * FROM OrderDetails WHERE OrderDetailID = @OrderDetailID;"; using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools())) { var orderDetail = connection.QuerySingleOrDefaultAsync<OrderDetail>(sql, new {OrderDetailID = 1}).Result; FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } ); }
Try it: .NET Core | .NET Framework
QuerySingleOrDefaultAsync
The QuerySingleOrDefaultAsync can execute a query and map asynchronously the first result, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.
string sql = "SELECT * FROM OrderDetails WHERE OrderDetailID = @OrderDetailID;"; using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools())) { var orderDetail = connection.QuerySingleOrDefaultAsync<OrderDetail>(sql, new {OrderDetailID = 1}).Result; FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } ); }
Try it: .NET Core | .NET Framework
QueryMultipleAsync
The QuerySingleOrDefaultAsync can execute multiple queries within the same command and map results asynchronously.
var sql = "SELECT TOP 3 * FROM Orders; SELECT TOP 3 * FROM OrderDetails;"; using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools())) { connection.Open(); using (var multi = connection.QueryMultipleAsync(sql).Result) { var orders = multi.Read<Order>().ToList(); var orderDetails = multi.Read<OrderDetail>().ToList(); FiddleHelper.WriteTable(orders); FiddleHelper.WriteTable(orderDetails); } }
Try it: .NET Core | .NET Framework