An EqualityComparer is not the way to go – it can only filter your result set in memory eg: var objects = yourResults.ToEnumerable().Distinct(yourEqualityComparer); You can use the GroupBy method to group by IDs and the First method to let your database only retrieve a unique entry per ID eg: var objects = yourResults.GroupBy(o => o.Id).Select(g … Read more
This can be done very simple, you were pretty close already SELECT distinct id, DENSE_RANK() OVER (ORDER BY id) AS RowNum FROM table WHERE fid = 64
If you don’t want to change your data model, you can use DISTINCT ON to fetch the newest record from table “b” for each entry in “a”: SELECT DISTINCT ON (a.id) * FROM a INNER JOIN b ON a.id=b.id ORDER BY a.id, b.date DESC If you want to avoid a “sort” in the query, adding … Read more
You can achieve the desired result by requesting a list of distinct ids instead of a list of distinct hydrated objects. Simply add this to your criteria: criteria.setProjection(Projections.distinct(Projections.property(“id”))); Now you’ll get the correct number of results according to your row-based limiting. The reason this works is because the projection will perform the distinctness check as … Read more
What you mean is either SELECT DISTINCT a, b FROM pairs; or SELECT a, b FROM pairs GROUP BY a, b;
You can use $addToSet with the aggregation framework to count distinct objects. For example: db.collectionName.aggregate([{ $group: {_id: null, uniqueValues: {$addToSet: “$fieldName”}} }]) Or extended to get your unique values into a proper list rather than a sub-document inside a null _id record: db.collectionName.aggregate([ { $group: {_id: null, myFieldName: {$addToSet: “$myFieldName”}}}, { $unwind: “$myFieldName” }, { … Read more
Try this: SELECT MIN(id) AS id, title FROM tbl_countries GROUP BY title
I know this is a rather old question, but I just went through a small example in my head which helped me understand why Postgres has this seemingly odd restriction on SELECT DISTINCT / ORDER BY columns. Imagine you have the following data in your Rsvp table: event_id | start_time ———-+———————— 0 | Mar 17, … Read more
How about simply: select distinct c1, c2 from t or select c1, c2, count(*) from t group by c1, c2
I assume that you use distinct like a method call on a list. You need to use the result of the query as datasource for your DropDownList, for example by materializing it via ToList. var distinctCategories = product .Select(m => new {m.CategoryId, m.CategoryName}) .Distinct() .ToList(); DropDownList1.DataSource = distinctCategories; DropDownList1.DataTextField = “CategoryName”; DropDownList1.DataValueField = “CategoryId”; Another … Read more