How to get the max value of id from second table using join in entity framework in ASP.NET C#

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i want to bind the only image in "a.BlogPicturePath" which is stored at its maximum Id value.

How do i use join query to get the max id value of second table?

What I have tried:

{
    try
    {
        using (database db = new database())
        {



            var query = (
                          from c in db.tblBlogs

                         join a in db.tblBlogMedias on c.id equals  a.BlogId



                         select new
                        {

                            c.id,
                            c.CreatedDate,
                            c.Author,
                            c.BlogTitle,
                            c.BlogDescription,
                            a.BlogId,
                            a.BlogPicturePath
                        }).OrderByDescending(d => d.id).ToList();



            System.Text.StringBuilder sb = new System.Text.StringBuilder();



                 query.ToList().ForEach(x =>
                    {



                            sb.Append(string.Format("<div class='post-thumb'><a href='#'><img class='img-responsive' src='{0}' alt=''></a><div class='post-meta'>"+
                                                     "</div>"+
                                                    "</div>"+
                                                    "<div class='entry-header'><h3><a href='#'>{1}</a></h3><span class='date'>{2}</span></div>",x.BlogPicturePath,x.BlogTitle,x.CreatedDate));


                    });





                 blogdiv.InnerHtml = sb.ToString();

                 Page.ClientScript.RegisterStartupScript(this.GetType(), "CallMyFunction", "activateReadmore()", true);


        }




    }
    catch (Exception ex)
    {
        Response.Write(ex.Message);
    }

}

Posted 1-Nov-17 2:49am

Umair Nafis

Updated 3-Nov-17 12:40pm

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Comments

Umair Nafis 1-Nov-17 13:31pm

how to write this query in entity framework . ie the code written above:

select tblBlog.*,tblBlogMedia.BlogPicturePath from tblBlog left outer join tblBlogMedia on tblBlog.id = tblBlogMedia.BlogId
where tblBlogMedia.id=(select max(id) from tblBlogMedia where BlogId='1')

here BlogId='1' is just for example i want samething like BlogId = @blogid

Karthik_Mahalingam 1-Nov-17 23:41pm

try something like this
result.Where(k=>k.id = result.Max(a=>a.id).where(b=>b.blogid = 1) )

Umair Nafis 3-Nov-17 15:06pm

How>?? what is result in this.? and where to use it ?

Karthik_Mahalingam 3-Nov-17 15:12pm

query

1 solution

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Umair Nafis · Answer 1 · 2017-11-03T12:40:00

Solution 1

var q = (from d in db.tblBlogMedias
                             join c in db.tblBlogs on d.BlogId equals x.id
                             select new
                             {
                                 d.Id,
                                 d.BlogPicturePath
                             }).OrderByDescending(d=>d.Id).Max(d => d.BlogPicturePath);

I write this query in foreach loop and it works pefectly fine. i just pass the value of q in sb.append

Posted 3-Nov-17 12:40pm

Umair Nafis

Comments

Richard Deeming 6-Nov-17 13:57pm

Calling OrderByDescending followed by Max doesn't make any sense. If you want the maximum value of a column, it doesn't matter what order the data is in.

If you just want the picture for the item with the highest ID, use:

.OrderByDescending(d => d.Id).Select(d => d.BlogPicturePath).FirstOrDefault()

Also, you don't need the join in that query, since you're not using anything from the tblBlogs table.

Umair Nafis 6-Nov-17 15:24pm

ohh yeah ! actually you are absolutely right and i didnt recognise it before. lol
Thank You Sir.