How do you use the MySql IN clause

Question

I am trying to figure out how to use the MySql In cluse with ASP.NET C#. Here is my code

var WebSites = string.Join(\",\", wsl.Select(x => \"\'\" + x.Doma         


        

Answer 1

I have found the answer. Here it is

    public static IList<Post> FindPostsByWebSiteList(string[] urls)
    {
        var pl = new List<Post>();
        var urlArray = urls.Select((x,y) => "@url" + y.ToString()).ToArray();
        var urlsJoined = string.Join(",", urlArray);
        string q = string.Format("select Id, Url, Title, Date, ImageUrl from post where WebSiteUrl IN ({0})", urlsJoined);

        using (MySqlConnection con = new MySqlConnection(WebConfigurationManager.ConnectionStrings["MySqlConnectionString"].ToString()))
        {
            using (MySqlCommand cmd = new MySqlCommand(q, con))
            {
                for (int x = 0; x < urlArray.Length; x++)
                {
                    cmd.Parameters.Add(urlArray[x], MySqlDbType.Text).Value = urls[x];
                }

                con.Open();

                var reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                while (reader.Read())
                {
                    var p = new Post();
                    p.Id = reader.GetInt32("Id");
                    p.Url = reader.GetString("Url");
                    p.Title = reader.GetString("Title");
                    p.Date = reader.GetDateTime("Date");
                    p.ImageUrl = reader.GetString("ImageUrl");
                    pl.Add(p);
                }
                return pl;
            }
        }
    }

Answer 2

You have referenced @Url instead of @Urls

maybe just a typo in your question though

Answer 3

The IN statement should expect an Array of strings, and you are passing a single string

Your final SQL is looking like this:

select Id, Url, Title, Date, ImageUrl from post where WebSiteUrl IN ('url1,url2,url3')

Instead of

select Id, Url, Title, Date, ImageUrl from post where WebSiteUrl IN ('url1', 'url2', 'url3')

Check this question:

Add List<int> to a mysql parameter