Dapper Async Methods Discover How to Execute Query Asynchronously

Description

Dapper has several methods that allow you to execute asynchronous queries. To use the async functionality, you need to pass in a System.Data.IDbConnection and call one of the extension methods provided by Dapper.

Dapper extends the IDbConnection interface with the following Async (asynchronous) methods.

ExecuteAsync: It executes a query asynchronously and returns the number of rows affected.
QueryAsync: It executes a query asynchronously and returns the results of the query as an IEnumerable<T>.
QueryFirstAsync: It executes a query asynchronously and returns the first result of the query.
QueryFirstOrDefaultAsync: It executes a query asynchronously and returns the first result of the query, or the default value for the type T if no result is found.
QuerySingleAsync: It executes a query asynchronously and returns a single result of the query.
QuerySingleOrDefaultAsync: It executes a query asynchronously and returns a single result of the query, or the default value for the type T if no result is found.
QueryMultipleAsync: It executes multiple queries asynchronously within the same command and maps the results to strong entities.

We only added a non-asynchronous version in this tutorial to make it easier to read.

ExecuteAsync

The ExecuteAsync method can execute a query one or multiple times asynchronously and return the number of affected rows. The following example shows how to use the ExecuteAsync method by inserting a customer

string sql = "INSERT INTO Customers (CustomerName) VALUES (@CustomerName);";

using (var connection = new SqlConnection(FiddleHelper.GetConnectionStringSqlServerW3Schools()))
{
	var affectedRows = await connection.ExecuteAsync(sql, new {CustomerName = "Mark"}).ConfigureAwait(false);

	Console.WriteLine(affectedRows);
	
	var customers = await connection.QueryAsync<Customer>("SELECT * FROM CUSTOMERS WHERE CustomerName = 'Mark'").ConfigureAwait(false);
	
	FiddleHelper.WriteTable(customers);
}

Try it: .NET Core

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 = await connection.QueryAsync<OrderDetail>(sql).ConfigureAwait(false);

	Console.WriteLine(orderDetails.Count());
	
	FiddleHelper.WriteTable(orderDetails);
}

Try it: .NET Core

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 = await connection.QueryFirstAsync<OrderDetail>(sql, new {OrderDetailID = 1}).ConfigureAwait(false);
	
	FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } );
}

Try it: .NET Core

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 = await connection.QueryFirstOrDefaultAsync<OrderDetail>(sql, new {OrderDetailID = 1}).ConfigureAwait(false);
	
	FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } );
}

Try it: .NET Core

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()))
{
	connection.Open();
	
	var orderDetail = await connection.QuerySingleAsync<OrderDetail>(sql, new {OrderDetailID = 1}).ConfigureAwait(false);

	FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } );
}

Try it: .NET Core

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 = await connection.QuerySingleOrDefaultAsync<OrderDetail>(sql, new {OrderDetailID = 1}).ConfigureAwait(false);
	
	FiddleHelper.WriteTable(new List<OrderDetail>() { orderDetail } );
}

Try it: .NET Core

QueryMultipleAsync

The QueryMultipleAsync 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 = await connection.QueryMultipleAsync(sql).ConfigureAwait(false))
	{
		var orders = multi.Read<Order>().ToList();
		var orderDetails = multi.Read<OrderDetail>().ToList();
		
		FiddleHelper.WriteTable(orders);
		FiddleHelper.WriteTable(orderDetails);
	}
}

Try it: .NET Core

Last updated: 2025-06-16
Author: ZZZ Projects

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Dapper Async Methods Discover How to Execute Query Asynchronously

Description

ExecuteAsync

QueryAsync

QueryFirstAsync

QueryFirstOrDefaultAsync

QuerySingleAsync

QuerySingleOrDefaultAsync

QueryMultipleAsync

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