如何在不使用EF的情况下连接ASP.NET Core Web API中的数据库？

Question

I am attempting to create an ASP.NET Core Web API without using EF Core. Instead, I would like to use System.Data.SQLClient to connect to SQL server, and query it using plain old SQL. That said, I'm having a bit of trouble figuring out how to establish the connection. I've found a lot of tutorials online that address how to do this with EF. But, I'm a bit perplexed as to how it's done without it.

Answer 1

You do it exactly the same way as you would in any .net application:

using (var conn = new System.Data.SqlClient.SqlConnection(connectionString)) {
    conn.Open();
    using (var cmd = conn.CreateCommand()) {
        cmd.CommandText = "SELECT 'hello world'";
        using (var reader = cmd.ExecuteReader()) {
            while (reader.Read()) {
                ...
            }
        }
    }
}

You will find that some parts of asp.net core require EF, like the identity claims stuff, so you will need to handle your own authentication and won't be able to use their security attributes and the like. I've gone this route on several asp.net core projects with no regrets

Answer 2

You must use SqlConnection and SqlCommand classes. From the documentation

private static void CreateCommand(string queryString, string connectionString)
{
    using (SqlConnection connection = new SqlConnection(
           connectionString))
    {
        SqlCommand command = new SqlCommand(queryString, connection);
        command.Connection.Open();
        command.ExecuteNonQuery();
    }
}

CreateCommand("insert into...", "[your connection string]");

Aditionally, Dapper is a good option for accessing data, is an object mapper that extends IDbConnection, so you don't have to worry about object creation. From dapper's docummentation

public class Dog
{
    public int? Age { get; set; }
    public Guid Id { get; set; }
    public string Name { get; set; }
    public float? Weight { get; set; }

    public int IgnoredProperty { get { return 1; } }
}            

var guid = Guid.NewGuid();
var dog = connection.Query<Dog>("select Age = @Age, Id = @Id", new { Age = (int?)null, Id = guid });