I am trying my first join and the sql that it's generating is very odd.
I have a Recipient belongs to a User. I am trying to query all the recipients by a user that are also not read and not deleted:
scope :unread, where(:is_read => false).where(:is_deleted => false)
scope :unread_by_user_id, lambda { |id| unread.joins(:user).merge(User.by_id(id)) }
This is the sql it generates:
SELECT `recipients`.* FROM `recipients` INNER JOIN `users` ON `users`.`id` IS NULL WHERE `recipients`.`is_read` = 0 AND `recipients`.`is_deleted` = 0 AND `users`.`id` = 475
Is there any way I can get rid of the "IS NULL"? That's not supposed to be there :(
I have tried searching google, and it's actually really amazing that 95% of examples out there do not talk about joins. The few examples of joins that I do find use the & syntax that has become depreciated. The documentation for this is actually quite bad compared to other things. Very odd indeed.
Anyway, I can't get this to work. It's definitely not a good day when you've been developing software for 19 years and can't get sql to join on a single table :( I can write queries in sql with 15 joins no problem manually. I guess that's the price you pay sometimes when you go through and learn new frameworks. It's not this weird though in Hibernate :/
Assuming you have your user fetched already:
user.recipients.unread
Recipients association already limits recipients to that user. Having a separate scope for that doesn't make sense to me.
--edit
This works if your User model has has_many :recipients association defined.
Related
I think my question is more related to SQL than to Laravel or its ORM, but I'm having the problem while programming in Laravel, so that's why I tagged it in the question.
My problem is as follows, I have the following model (sorry for the Spanglish):
I have the users table, nothing special here,
Then the juegos (games) tables, in it there's a jornada column (its like the week, to know which games are played in a certain week)
And finally the pronosticos (who the user says will win, which is stored in the diferencia column)
So I want to make a form where the user can make his bet. Basically this form will take its data from the pronosticos table, like this:
$juegos = Juego::where('jornada', $jor)
-> orderBy('expira')
-> get();
This produces what I want, a collection of models that I can iterate to show all the games for a given jornada (week).
Now, if the user has already make its bet, I want to bring also the scores values the user is betting on, with a query, so I thought I could use something like:
$juegos = Juego::where('jornada', $jor)
-> leftJoin('pronosticos', 'juegos.id', '=', 'pronosticos.juego_id')
-> addSelect(['pronosticos.user_id', 'juegos.id', 'expira', 'visitante', 'local', 'diferencia'])
-> having('pronosticos.user_id', $uid)
-> orderBy('expira')
-> get();
Now, the problem is, it is bringing an empty set, and thats quite obvious, if the user has made his bet, it will work, but if he hasn't the having will filter out everything, giving the empty set.
So I think I'm not getting clearly how to make the having or where to work correctly. Maybe what I want is to do a leftJoin not with the pronosticos table, but from the pronosticos table already filtered with a where clause.
Maybe I'm doing everything wrong and should do the leftJoin to a subselect? If that's so, I have no idea how to do it.
Or maybe my expectations are outside what can be done to SQL and I may return two different sets, and process them in the app?
EDIT
This is the query I want to express in Laravel's ORM:
SELECT * from juegos
LEFT JOIN (SELECT * FROM pronosticos WHERE user_id=1) AS p
ON p.juego_id = juegos.id
WHERE jornada = 2 ORDER BY expira
I feel foolish, but I cannot find the answer to this.
If I have a User with many attributes, given a list of attributes, I can ask rails something like this:
User.where("attributes.id IN ?", list_of_attribute_ids)
With the appropriate joins or includes or whatever.
However, I have no idea how to find the inverse set of those users. That is, given 100 users, if the result return 75 entries, I don't know how to find the other 25!
I thought
User.where("attributes.id NOT IN ?", list_of_attribute_ids)
might work (similarly, User.where.not), but it doesn't! Instead, it looks for those users where any of their attributes are not one of the list, which is useful, but not what I want.
The only way I know how to do it, is with something like:
User.where.not(id: User.where("attributes.id IN ?", list_of_attribute_ids).pluck(:id))
Which is sort of like the SQL for select user where id not in (gather a list of ids).
But this is massively non-performant, and generally just can't cope with a database with more than a few (hundred) entries.
How do you do this?
I think you could use left outer joins, like #Vishal mentioned in the comments.
See the guides: http://guides.rubyonrails.org/active_record_querying.html#left-outer-joins
rails 4:
joins("LEFT OUTER JOIN <something>")
rails 5:
left_outer_joins(:something)
I have joined a new job where I am required to use FileMaker (and gradually transition systems to other databases). I have been a DB Admin of a MS SQL Server database for ~2 years, and I am very well versed in PL/SQL and T-SQL. I am trying to pan my SQL knowledge to FMP using the ExecuteSQL functionaloty, and I'm kinda running into a lot of small pains :)
I have 2 tables: Movies and Genres. The relevant columns are:
Movies(MovieId, MovieName, GenreId, Rating)
Genres(GenreId, GenreName)
I'm trying to find the movie with the highest rating in each genre. The SQL query for this would be:
SELECT M.MovieName
FROM Movies M INNER JOIN Genres G ON M.GenreId=G.GenreId
WHERE M.Rating=
(
SELECT MAX(Rating) FROM Movies WHERE GenreId = M.GenreId
)
I translated this as best as I could to an ExecuteSQL query:
ExecuteSQL ("
SELECT M::MovieName FROM Movies M INNER JOIN Genres G ON M::GenreId=G::GenreId
WHERE M::Rating =
(SELECT MAX(M2::Rating) FROM Movies M2 WHERE M2::GenreId = M::GenreId)
"; "" ; "")
I set the field type to Text and also ensured values are not stored. But all I see are '?' marks.
What am I doing incorrectly here? I'm sorry if it's something really stupid, but I'm new to FMP and any suggestions would be appreciated.
Thank you!
--
Ram
UPDATE: Solution and the thought process it took to get there:
Thanks to everyone that helped me solve the problem. You guys made me realize that traditional SQL thought process does not exactly pan to FMP, and when I probed around, what I realized is that to best use SQL knowledge in FMP, I should be considering each column independently and not think of the entire result set when I write a query. This would mean that for my current functionality, the JOIN is no longer necessary. The JOIN was to bring in the GenreName, which is a different column that FMP automatically maps. I just needed to remove the JOIN, and it works perfectly.
TL;DR: The thought process context should be the current column, not the entire expected result set.
Once again, thank you #MissJack, #Chuck (how did you even get that username?), #pft221 and #michael.hor257k
I've found that FileMaker is very particular in its formatting of queries using the ExecuteSQL function. In many cases, standard SQL syntax will work fine, but in some cases you have to make some slight (but important) tweaks.
I can see two things here that might be causing the problem...
ExecuteSQL ("
SELECT M::MovieName FROM Movies M INNER JOIN Genres G ON
M::GenreId=G::GenreId
WHERE M::Rating =
(SELECT MAX(M2::Rating) FROM Movies M2 WHERE M2::GenreId = M::GenreId)
"; "" ; "")
You can't use the standard FMP table::field format inside the query.
Within the quotes inside the ExecuteSQL function, you should follow the SQL format of table.column. So M::MovieName should be M.MovieName.
I don't see an AS anywhere in your code.
In order to create an alias, you must state it explicitly. For example, in your FROM, it should be Movies AS M.
I think if you fix those two things, it should probably work. However, I've had some trouble with JOINs myself, as my primary experience is with FMP, and I'm only just now becoming more familiar with SQL syntax.
Because it's incredibly hard to debug SQL in FMP, the best advice I can give you here is to start small. Begin with a very basic query, and once you're sure that's working, gradually add more complicated elements one at a time until you encounter the dreaded ?.
There's a number of great posts on FileMaker Hacks all about ExecuteSQL:
Since you're already familiar with SQL, I'd start with this one: The Missing FM 12 ExecuteSQL Reference. There's a link to a PDF of the entire article if you scroll down to the bottom of the post.
I was going to recommend a few more specific articles (like the series on Robust Coding, or Dynamic Parameters), but since I'm new here and I can't include more than 2 links, just go to FileMaker Hacks and search for "ExecuteSQL". You'll find a number of useful posts.
NB If you're using FMP Advanced, the Data Viewer is a great tool for testing SQL. But beware: complex queries on large databases can sometimes send it into fits and freeze the program.
The first thing to keep in mind when working with FileMaker and ExecuteSQL() is the difference between tables and table occurrences. This is a concept that's somewhat unique to FileMaker. Succinctly, tables store the data, but table occurrences define the context of that data. Table occurrences are what you're seeing in FileMaker's relationship graph, and the ExecuteSQL() function needs to reference the table occurrences in its query.
I agree with MissJack regarding the need to start small in building the SQL statement and use the Data Viewer in FileMaker Pro Advanced, but there's one more recommendation I can offer, which is to use SeedCode's SQL Explorer. It does require the adding of table occurrences and fields to duplicate the naming in your existing solution, but this is pretty easy to do and the file they offer includes a wizard for building the SQL query.
I have a complicated query I need for a scope in my Rails app and have tried a lot of things with no luck. I've resorted to raw SQL via find_by_sql but wondering if any gurus wanted to take a shot. I will simplify the verbiage a bit for clarity, but the problem should be stated accurately.
I have Users. Users own many Records. One of them is marked current (#is_current = true) and the rest are not. Each CoiRecord has many Relationships. Relationships have a value for when they were active (active_when) which takes four values, [1..4].
Values 1 and 2 are considered recent. Values 3 and 4 are not.
The problem was ultimately to have a scopes (has_recent_relationships and has_no_recent_relationships) on User that filters on whether or not they have recent Relationships on current Record. (Old Records are irrelevant for this.) I tried create a recent and not_recent scope on Relationship, and then building the scopes on Record, combining with checking for is_current == 1. Here is where I failed. I have to move on with the app but have no choice but to use raw SQL and continue the app, hoping to revisit this later. I put that on User, the only context I really need it, and set aside the code for the scopes on the other objects.
The SQL that works, that correctly finds the Users who have recent relationships is below. The other just uses "= 0" instead "> 0" in the HAVING clause.
SELECT * FROM users WHERE `users`.`id` IN (
SELECT
records.owner_id
FROM `coi_records`
LEFT OUTER JOIN `relationships` ON `relationships`.`record_id` = `records`.`id`
WHERE `records`.`is_current` = 1
HAVING (
SELECT count(*)
FROM relationships
WHERE ((record_id = records.id) AND ((active_when = 1) OR (active_when = 2)))
) > 0
)
My instincts tell me this is complicated enough that my modeling probably could be redesigned and simplified, but the individual objects are pretty simple, just getting at this specific data from two objects away has become complicated.
Anyway, I'd appreciate any thoughts. I'm not expecting a full solution because, ick. Just thought the masochists among you might find this amusing.
Have you tried using Arel directly and this website?
Just copy-and-pasting your query you get this:
User.select(Arel.star).where(
User.arel_table[:id].in(
Relationship.select(Arel.star.count).where(
Arel::Nodes::Group.new(
Relationship.arel_table[:record_id].eq(Record.arel_table[:id]).and(
Relationship.arel_table[:active_when].eq(1).or(Relationship.arel_table[:active_when].eq(2))
)
)
).joins(
CoiRecord.arel_table.join(Relationship.arel_table, Arel::Nodes::OuterJoin).on(
Relationship.arel_table[:record_id].eq(Record.arel_table[:id])
).join_sources
).ast
)
)
I managed to find a way to create what I needed which returns ActiveRelationship objects, which simplifies a lot of other code. Here's what I came up with. This might not scale well, but this app will probably not end up with so much data that it will be a problem.
I created two scope methods. The second depends on the first to simplify things:
def self.has_recent_relationships
joins(records_owned: :relationships)
.merge(Record.current)
.where("(active_when = 1) OR (active_when = 2)")
.distinct
end
def self.has_no_recent_relationships
users_with_recent_relationships = User.has_recent_relationships.pluck(:id)
if users_with_recent_relationships.length == 0
User.all
else
User.where("id not in (?)", users_with_recent_relationships.to_a)
end
end
The first finds Users with recent relationships by just joining Record, merging with a scope that selects current records (should be only one), and looks for the correct active_when values. Easy enough.
The second method finds Users who DO have recent relationships (using the first method.) If there are none, then all Users are in the set of those with no recent relationships, and I return User.all (this will really never happen in the wild, but in theory it could.) Otherwise I return the inverse of those who do have recent relationships, using the SQL keywords NOT IN and an array. It's this part that could be non-performant if the array gets large, but I'm going with it for the moment.
Helo,
My query:
#county = County.joins(:state)
.where("counties.slug = ? AND states.slug = ?", params[:county_slug])
.select('states.*, counties.*')
.first!
From the log, the SQL looks like this:
SELECT states.*, counties.* FROM "counties" INNER JOIN "states" ON "states"."id" = "counties"."state_id" LIMIT 1
My problem is that is doesn't eager load the data from the associated table (states), because when I do, for example, #county.state.name, it runs another query, although, as you can see from the log, it had already queried the database for the data in that table as well. But it doesn't pre populate #county.state
Any idea how i can get all the data from the database in just ONE query?
Thx
I think you need to use include instead of joins to get the eager loading. There's a good railscasts episode about the differences: http://railscasts.com/episodes/181-include-vs-joins , in particular:
The question we need to ask is “are we using any of the related model’s attributes?” In our case the answer is “yes” as we’re showing the user’s name against each comment. This means that we want to get the users at the same time as we retrieve the comments and so we should be using include here.