Adding select distinct to linq query - linq

Question

My Web API Controller has a method that retrieves a specified number of decriptions from a database table. There are duplicate descriptions with different IDs, so sometimes the query returns duplicates when I use SELECT TOP. I also added random (ORDER BY NEWID) to lessen the chances of getting dups but duplicates still get returned sometimes. I want to change the query to SELECT DISTINCT but not sure how to do that in my particular case. Using First() seems to be complicated here. Can anyone help? My method is below:
public List<String> GetRandomDescriptions(string cat, string subcat, int n)
{
using (MyContext ctx = new MyContext())
{
var temp = ctx.Interactions.Where(d => (d.Category.Equals(cat) && d.Subcategory.Equals(subcat)))).OrderBy(d=>Guid.NewGuid()).Take(n).Select(d=>d.Description).ToList();
return temp;
}
}
Here is my class:
[Table("[Records]")]
public class Interaction
{
[Key, Column("RECORD_ID")]
public string DescId { get; set;}
public string Category { get; set; }
public string Subcategory { get; set; }
public string Description{get; set;}
}

Answer 1

You can use something like this
var result = ctx.Interactions
.Where(d => d.Category == cat && d.Subcategory == subcat)
.Select(d => d.Description)
.Distinct()
.Take(n)
.ToList();
The key points are - first apply the filter, then select the description, then make it distinct and finally take the required number of items.
If you really need to pick a random items, then just insert your OrderBy before Take.

Answer 2

You don't need to do the funny OrderBy construct. Try something like this:
public List<String> GetRandomDescriptions(string cat, string subcat, int n)
{
using (MyContext ctx = new MyContext())
{
var temp = ctx.Interactions
.Where(d => d.Category.Equals(cat) && d.Subcategory.Equals(subcat)))
.Select(d=>d.Description)
.Distinct()
.ToList();
return temp;
}
}