ExecuteReader

This method is used to execute a raw-SQL directly towards the database. It returns an instance of DbDataReader object. This method supports all types of RDMBS data providers.

Code Snippets

Below is a code that reads all the rows from the [dbo].[Person] table from the database.

using (var connection = new SqlConnection(connectionString))
{
    using (var reader = connection.ExecuteReader("SELECT * FROM [dbo].[Person];"))
    {
        // Do more stuffs for the reader here
    }
}

Passing of Parameters

You can pass a parameter via the following objects.

IDbDataParameter
Anonymous Types
ExpandoObject
Dictionary<string, object>
QueryField/QueryGroup

IDbDataParameter

using (var connection = new SqlConnection(connectionString))
{
    using (var reader = connection.ExecuteReader("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", new { Id = new SqlParameter("_", 10045) }))
    {
        // Do more stuffs for the reader here
    }
}

The name of the parameter is not required. The library is replacing it with the actual name of the property passed from the object.

Anonymous Types

using (var connection = new SqlConnection(connectionString))
{
    using (var reader = connection.ExecuteReader("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", new { Id = 10045 }))
    {
        // Do more stuffs for the reader here
    }
}

ExpandoObject

using (var connection = new SqlConnection(connectionString))
{
    var param = new ExpandoObject() as IDictionary<string, object>;
    param.Add("Id", 10045);
    using (var reader = connection.ExecuteReader("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param))
    {
        // Do more stuffs for the reader here
    }
}

Dictionary<string, object>

using (var connection = new SqlConnection(connectionString))
{
    var param = new Dictionary<string, object>
    {
        { "Id", 10045 }
    };
    using (var reader = connection.ExecuteReader("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param))
    {
        // Do more stuffs for the reader here
    }
}

QueryField/QueryGroup

using (var connection = new SqlConnection(connectionString))
{
    var param = new []
    {
        new QueryField("Id", 10045)
    };
    using (var reader = connection.ExecuteReader("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param))
    {
        // Do more stuffs for the reader here
    }
}

Or via QueryGroup.

using (var connection = new SqlConnection(connectionString))
{
    var param = new QueryGroup(new []
    {
        new QueryField("Id", 10045)
    });
    using (var reader = connection.ExecuteReader("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param))
    {
        // Do more stuffs for the reader here
    }
}

Array Parameters (for the IN keyword)

You can pass an array of values if you are using the IN keyword.

using (var connection = new SqlConnection(connectionString))
{
    var param = new
    {
        Keys = new [] { 10045, 10102, 11004 }
    };
    using (var reader = connection.ExecuteReader("SELECT * FROM dbo].[Person] WHERE Id IN (@Keys);", param))
    {
        // Do more stuffs for the reader here
    }
}

You can also use the types defined at the Passing of Parameters section when passing a parameter.

Executing a Stored Procedure

There are 2 ways of executing a stored procedure. First, simply pass the name of the stored procedure and set the command type to CommandType.StoredProcedure.

using (var connection = new SqlConnection(connectionString))
{
    using (var reader = connection.ExecuteReader("[dbo].[sp_GetPerson]", new { Id = 10045 }, commandType: CommandType.StoredProcedure))
    {
        // Do more stuffs for the reader here
    }
}

Or, simply use the native SQL calls like below.

using (var connection = new SqlConnection(connectionString))
{
    using (var reader = connection.ExecuteReader("EXEC [dbo].[sp_GetPerson](@Id);", new { Id = 10045 }))
    {
        // Do more stuffs for the reader here
    }
}

Notice in the second call, there is semi-colon at the end of the command text and the command type was not set.