以下是一个示例，演示了如何在ASP.NET中使用DAO而不是Entity Framework来创建REST API。

首先，我们需要定义一个数据访问对象（DAO）类，该类将负责与数据库进行交互。在这个例子中，我们将使用ADO.NET来执行数据库操作。

public class ProductDAO
{
    private string connectionString;

    public ProductDAO(string connectionString)
    {
        this.connectionString = connectionString;
    }

    public List GetAllProducts()
    {
        List products = new List();

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            string query = "SELECT * FROM Products";
            SqlCommand command = new SqlCommand(query, connection);
            SqlDataReader reader = command.ExecuteReader();

            while (reader.Read())
            {
                Product product = new Product();
                product.Id = reader.GetInt32(0);
                product.Name = reader.GetString(1);
                product.Price = reader.GetDecimal(2);

                products.Add(product);
            }

            reader.Close();
        }

        return products;
    }

    public Product GetProductById(int id)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            string query = "SELECT * FROM Products WHERE Id = @Id";
            SqlCommand command = new SqlCommand(query, connection);
            command.Parameters.AddWithValue("@Id", id);
            SqlDataReader reader = command.ExecuteReader();

            if (reader.Read())
            {
                Product product = new Product();
                product.Id = reader.GetInt32(0);
                product.Name = reader.GetString(1);
                product.Price = reader.GetDecimal(2);

                reader.Close();

                return product;
            }
        }

        return null;
    }

    public void AddProduct(Product product)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            string query = "INSERT INTO Products (Name, Price) VALUES (@Name, @Price)";
            SqlCommand command = new SqlCommand(query, connection);
            command.Parameters.AddWithValue("@Name", product.Name);
            command.Parameters.AddWithValue("@Price", product.Price);
            command.ExecuteNonQuery();
        }
    }

    public void UpdateProduct(Product product)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            string query = "UPDATE Products SET Name = @Name, Price = @Price WHERE Id = @Id";
            SqlCommand command = new SqlCommand(query, connection);
            command.Parameters.AddWithValue("@Name", product.Name);
            command.Parameters.AddWithValue("@Price", product.Price);
            command.Parameters.AddWithValue("@Id", product.Id);
            command.ExecuteNonQuery();
        }
    }

    public void DeleteProduct(int id)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            string query = "DELETE FROM Products WHERE Id = @Id";
            SqlCommand command = new SqlCommand(query, connection);
            command.Parameters.AddWithValue("@Id", id);
            command.ExecuteNonQuery();
        }
    }
}

接下来，我们需要创建一个控制器类来处理REST API的请求。

[Route("api/[controller]")]
[ApiController]
public class ProductsController : ControllerBase
{
    private ProductDAO productDAO;

    public ProductsController(IConfiguration configuration)
    {
        string connectionString = configuration.GetConnectionString("DefaultConnection");
        productDAO = new ProductDAO(connectionString);
    }

    [HttpGet]
    public ActionResult> Get()
    {
        List products = productDAO.GetAllProducts();
        return products;
    }

    [HttpGet("{id}")]
    public ActionResult Get(int id)
    {
        Product product = productDAO.GetProductById(id);

        if (product == null)
        {
            return NotFound();
        }

        return product;
    }

    [HttpPost]
    public ActionResult Post(Product product)
    {
        productDAO.AddProduct(product);
        return Ok();
    }

    [HttpPut("{id}")]
    public ActionResult Put(int id, Product product)
    {
        if (id != product.Id)
        {
            return BadRequest();
        }

        productDAO.UpdateProduct(product);
        return Ok();
    }

    [HttpDelete("{id}")]
    public ActionResult Delete(int id)
    {
        productDAO.DeleteProduct(id);
        return Ok();
    }
}

最后，我们需要将依赖项注入到Startup.cs文件中。

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient(_ => Configuration);

    services.AddControllers();

    // 添加数据库连接字符串
    services.AddDbContext(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    // 注册ProductDAO
    services.AddScoped();

    // 其他配置...
}

这是一个简单的示例，演示了如何在ASP.NET中使用DAO而不是