distinct

** EDIT ** Nevermind, just needed to take out the parens... I get this error: ERROR: could not identify an ordering operator for type record when trying to use DISTINCT Here's the query: select DISTINCT(g.fielda, g.fieldb, r.type) from fields g LEFT JOIN types r ON g.id = r.id; And the errors: ERROR: could not identify an ordering operator for type record HINT: Use an explicit ordering operator or modify the query. ********** Error ********** ERROR: could not identify an ordering operator for type record SQL state: 42883 Hint: Use an explicit ordering operator or modify the query. As I think

so I'm working on a django application where I have a model Event. Each Event has some attributes, say one of them is "hostname" (which I will use throughout as an example). I need to implement search functionality where a user can search for all events that has hostname == some_value, e.g. hostname == "myhost.foo.bar". Now, I wanted to allow the user to select among the valid options (i.e. the hostnames that actually exist in one or more event) in a combobox in the search form, so I use ModelChoiceFields for my form. My subclass of ModelChoiceView, for displaying the correct label: class

class State < ActiveRecord::Base has_many :cities end class City < ActiveRecord::Base belongs_to :state has_many :companies end class Company < ActiveRecord::Base belongs_to :city end I'm trying to list all states, and their respective cities, that contain at least one company registered. My first try was the following query: states = State.joins(:cities => :companies).includes(:cities) Which works, but I end up getting duplicates if a state has more than one city with companies in it. I then changed the query to: states = State.joins(:cities => :companies).includes(:cities).select("distinct

I just wondered if anyone has run into a case in SQLite (3.7.4) where a query would return one set of results, and when it becomes a subquery the results are completely different? I found the problem in a more complex query, but here's a simpler example that demonstrates the same behavior: Database setup: CREATE TABLE "test" ("letter" VARCHAR(1) PRIMARY KEY, "number" INTEGER NOT NULL); INSERT INTO "test" ("letter", "number") VALUES('b', 1); INSERT INTO "test" ("letter", "number") VALUES('a', 2); INSERT INTO "test" ("letter", "number") VALUES('c', 2); Initial query: SELECT "letter", "number"

I have two ways that I am doing a fuzzy search for a customer. One is by an abbreviated name and the other is by the customer's full name. When I take these two result sets and then union them together (which I have read several places should remove distinct values) I get duplicates. Thinking that all I need to do is then call the .Distinct() method on this, I also still get duplicates. Do I need to implement some compare functionality in my customer object? My code: Dim shortNameMatch As List(Of ICustomer) = CustomerLibrary.GetCustomersByShortName(term) Dim custNameMatch As List(Of ICustomer)

I have 3 tables: Vehicle: vehicle_id, vehicle_type 1, motorcycle 2, car 3, van Owners: person_id, vehicle_id, date_bought 1, 1, 2009 1, 2, 2008 2, 3, 2009 2, 1, 2005 I want to display a list of all vehicle names. If the person_id = 1 , date_bought should also be returned. So I thought I would start with this: SELECT * FROM vehicles LEFT JOIN Owners USING (vehicle_id) which returns this: 1, 1, motorcycle, 2009 1, 2, car, 2008 2, 3, van, 2009 2, 1, motorcycle, 2005 However, I now cannot narrow this down to the needed result. If I use DISTINCT(car_id) , there is no change as I am already choosing

I have a table GL that contains GLCode. I need to get a list of unique GLCodes, but get all the other columns. The following SQL produces the results I want. select * from GL where GLId in (select Min(GLId) from GL group by GLCode ) Is there a way to do this using the Criteria API? This is my best attempt: var subQuery = DetachedCriteria.For<GL>(); subQuery .SetProjection(Projections.Property("GLCode")) .SetResultTransformer(new DistinctRootEntityResultTransformer()); return (List<GL>)currentSession .CreateCriteria(typeof(GL)) .Add(Subqueries.PropertyIn("GLCode", subQuery)) .List<GL>(); Even

I use the following code for creating table: CREATE KEYSPACE mykeyspace WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 }; USE mykeyspace; CREATE TABLE users ( user_id int PRIMARY KEY, fname text, lname text ); INSERT INTO users (user_id, fname, lname) VALUES (1745, 'john', 'smith'); INSERT INTO users (user_id, fname, lname) VALUES (1744, 'john', 'doe'); INSERT INTO users (user_id, fname, lname) VALUES (1746, 'john', 'smith'); I would like to find the distinct value of lname column (that is not a PRIMARY KEY). I would like to get the following result: lname -------

mysql DISTINCT语句 语法 作用： 用于返回唯一不同的值。 语法： SELECT DISTINCT 列名称 FROM 表名称。 扬州大理石量具 mysql DISTINCT语句 示例 //从表中选取唯一不同的值 SELECT DISTINCT 列名称 FROM 表名; 来源： https://www.cnblogs.com/furuihua/p/11904491.html

In the DB I am working with, I want to select only the year from a specific TimeStamp field. In particular, I'm hoping to select the unique years from this database column. For instance, if all of the timestamps in the field "ModifyTimeStamp" are either from the year 2002 or the year 2006, I would like returned simply a result of '2002' and '2006'. If this is impossible, I'd be content with getting a result of a bunch of '2002's mixed with '2006's and would parse it later. All I've been able to get working so far is "Select ModifyTimeStamp from Table" - all my attempts to parse have failed. I