I'm trying to conditionally join one master event table to three others depending on an event type. The select statement works fine, and returns the result set I'd expect, but when I add the JOIN statements, I get an error saying the column aliases were not found:
SELECT
event.type as type,
IF(type = 'birthday', event.target_id, NULL) as birthday_id,
IF(type = 'graduation', event.target_id, NULL) as graduation_id,
IF(type = 'wedding', event.target_id, NULL) as wedding_id
FROM event
LEFT OUTER JOIN birthday ON birthday_id = birthday.id
LEFT OUTER JOIN graduation ON graduation_id = graduation.id
LEFT OUTER JOIN wedding ON wedding_id = wedding.id
Gets this error:
Unknown column 'birthday_id' in 'on clause'
UPDATE: Ok Sebas just indicated you can't join on calculation results, in which case my approach is off. So what is the correct approach for doing something like this?
SELECT
event.type as type,
IF(type = 'birthday', birthday.id, NULL) as birthday_id,
IF(type = 'graduation', graduation.id, NULL) as graduation_id,
IF(type = 'wedding', wedding.id, NULL) as wedding_id
FROM
event
LEFT OUTER JOIN birthday b ON event.target_id = b.id
LEFT OUTER JOIN graduation g ON b.id IS NULL AND event.target_id = g.id
LEFT OUTER JOIN wedding w ON b.id IS NULL AND g.id IS NULL AND event.target_id = w.id
should do the trick, give me feedback!
rgds.
edit: See the IS NULL conditions. I didn't test it, I wonder if mysql would accept it! If yes, then almost only the necessary joins would be done...
You need to join all of the tables with the same field, event.target_id, and when you need to show some specific data, you can test the type before.
Example:
SELECT
event.type as type,
IF(type = 'birthday', birthday.birthday_id, NULL) as birthday,
IF(type = 'graduation', graduation.graduation_id, NULL) as graduation,
IF(type = 'wedding', wedding.wedding_id, NULL) as wedding
FROM event
LEFT OUTER JOIN birthday ON birthday_id = event.target_id
LEFT OUTER JOIN graduation ON graduation_id = event.target_id
LEFT OUTER JOIN wedding ON wedding_id = event.target_id
Not testes, but hope this helps you elucidate your doubts.
Sebas answer is correct but need not conditions to check IS NULL for each previous joins, you can use based column value to make it effective. I have tested this and its working.
SELECT
E.type AS type,
IF(E.type = 'birthday', B.id, NULL) AS birthday_id,
IF(E.type = 'graduation', G.id, NULL) AS graduation_id,
IF(E.type = 'wedding', W.id, NULL) AS wedding_id
FROM event E
LEFT OUTER JOIN birthday B ON E.type = 'birthday' AND E.target_id = B.id
LEFT OUTER JOIN graduation G ON E.type = 'graduation' AND E.target_id = G.id
LEFT OUTER JOIN wedding W ON E.type = 'wedding' AND E.target_id = W.id
Related
$sql = "SELECT cc.name AS c_name, ev.name AS event_name, ev.eventModeId AS event_mode, ev.carClassHash, cc.carClassHash
FROM EVENT_DATA e
INNER JOIN PERSONA p ON e.personaId = p.ID
INNER JOIN CUSTOMCAR cc ON cc.ownedCarId = e.carId
INNER JOIN CAR_CLASSES ccs ON ccs.store_name = cc.name
INNER JOIN USER u ON u.ID = p.USERID
LEFT JOIN BAN b ON b.user_id = u.ID
INNER JOIN EVENT ev ON ev.ID = e.EVENTID
WHERE (p.name = ?
AND ev.carClassHash = cc.carClassHash)";
This query works for me except I'd also like to display any carClassHash with the value '607077938'. Is there a way I could somehow keep the above query to check if the event hash matches the car class hash but also still display values where the carClassHash (cc.carClassHash) is equal to '607077938'?
Thanks! :)
Why not use OR in the WHERE clause?
[...]
WHERE ((p.name = ? AND ev.carClassHash = cc.carClassHash) OR (cc.carClassHash = 607077938))
This should work if that value is an integer. If it's a string, use quotes around it.
looking for a bit of help here if possible?
I have the following query:-
On or database we have a table called Linkfile, in this table are "Types" all beginning with "YG". I need to return those rows that do not have the type of "YG8" but just cannot seem to do it. I know ill need to use a sub query but am stuck!
This is my code and the fields I need to return. I just need to only show those that do not have the lk.type of "YG8"
select distinct l.description, p.displayname AS Temp, p.compliance_status As 'Compliant', lk.displayname, lk.type
from event e
inner join organisation o on e.organisation_ref = o.organisation_ref
inner join opportunity opp on e.opportunity_ref = opp.opportunity_ref
inner join event_role ev on ev.event_ref = e.event_ref
inner join address a on a.address_ref = opp.address_ref
inner join person p on ev.person_ref = p.person_ref
inner join lookup l on p.responsible_team = l.code
inner join person_type pt on p.person_ref = pt.person_ref
inner join linkfile lk on lk.parent_object_ref = pt.person_ref
where o.displayname LIKE '%G4S%' and p.compliance_category = '$016'
and lk.type like 'YG%' and l.code_type = '2'
and a.displayname LIKE '%MOJ%'
and pt.status = 'A'
order by l.description, p.displayname, lk.type
Use below query :
select distinct l.description, p.displayname AS Temp, p.compliance_status As 'Compliant', lk.displayname, lk.type,lk.parent_object_ref
from event e
inner join organisation o on e.organisation_ref = o.organisation_ref
inner join opportunity opp on e.opportunity_ref = opp.opportunity_ref
inner join event_role ev on ev.event_ref = e.event_ref
inner join address a on a.address_ref = opp.address_ref
inner join person p on ev.person_ref = p.person_ref
inner join lookup l on p.responsible_team = l.code
inner join person_type pt on p.person_ref = pt.person_ref
left join (select displayname, type,parent_object_ref from linkfile where lk.type like 'YG8%' )lk on lk.parent_object_ref = pt.person_ref
where o.displayname LIKE '%G4S%' and p.compliance_category = '$016' and lk.parent_object_ref is null
and l.code_type = '2'
and a.displayname LIKE '%MOJ%'
and pt.status = 'A'
order by l.description, p.displayname, lk.type;
I've used left join on linkfile with type like 'YG8%' and fetching the only records which are not matched
I think you can just replace the
lk.type like 'YG%'
with the following:
(lk.type >= 'YG' and lk.type <'YG8') or (lk.type > 'YG8' and lk.type <='YGZ')
this should accomplish what you are trying to do and also avoid using "like" which is less efficient (assuming you have an index on lk.type, at least).
You may refine this a bit by knowing which are the possible values of lk.type of course. I.e. what are the extremes for the YG "subtype"? YG00-YG99? YG-YGZ?
(Be especially careful if you may have YG81 or YG87 for example, because then my clause will not work properly... on the other hand if your YG subtype can have values like YG34 it would have been better to use YG08 instead of YG8)
I have a query with a CASE statement that determines the variable object_name this variable is derived from either the x_ambitions table or the x_trybes table. The queries below were combined so that I could keep it simple by just executing one SQL query.
I've split the SELECT statement into two so that you have a better understanding. The two queries below. Work and pull the correct object_name from the database.
The problem I'm having when I combine the two queries is that the cases 'new_join_ambition','new_created_ambition','new_liked_ambition' object_name returns NULL in the LEFT JOIN.
In the combined query, If I bring the cases: 'new_join_ambition','new_created_ambition','new_liked_ambition' above the 'new_join_trybe','new_created_trybe','new_liked_trybe' cases. The opposite happens. The trybe rows return NULL.
The two SQL queries:
A: (Retrieve Object A)
SELECT
s.id,
s.object_id,
s.type,
s.postee_id,
s.user_id,
s.text,
s.registered,
CONCAT(u.x_first_name,' ',u.x_last_name) AS postee_name,
ui.image_id AS postee_image_id,
CASE s.type
WHEN 'new_join_ambition'
OR 'new_created_ambition'
OR 'new_liked_ambition'
THEN a.name
ELSE 'a'
END AS object_name
FROM
x_share s
LEFT JOIN
x_user u ON u.id = s.postee_id
LEFT JOIN
x_user_images ui ON ui.user_id = s.postee_id
LEFT JOIN
x_ambitions a ON s.type IN ('new_join_ambition', 'new_created_ambition', 'new_liked_ambition') AND s.object_id = a.id
LEFT JOIN
x_ambition_invites ai ON s.type IN ('new_join_ambition') AND s.object_id = ai.ambition_id AND s.postee_id = ai.to
LEFT JOIN
x_ambition_likes al ON s.type IN ('new_liked_ambition') AND s.object_id = al.ambition_id AND s.postee_id = al.profile_id
LEFT JOIN
x_ambition_owner aoo ON s.type IN ('new_created_ambition') AND s.object_id = aoo.ambition_id
WHERE
s.user_id = '%s'
ORDER BY
s.registered DESC
B: (Retrieve Object B)
SELECT
s.id,
s.object_id,
s.type,
s.postee_id,
s.user_id,
s.text,
s.registered,
CONCAT(u.x_first_name,' ',u.x_last_name) AS postee_name,
ui.image_id AS postee_image_id,
CASE s.type
WHEN 'new_join_trybe'
OR 'new_created_trybe'
OR 'new_liked_trybe'
THEN t.name
ELSE 'a'
END AS object_name
FROM
x_share s
LEFT JOIN
x_user u ON u.id = s.postee_id
LEFT JOIN
x_user_images ui ON ui.user_id = s.postee_id
LEFT JOIN
x_trybes t ON s.type IN ('new_join_trybe', 'new_created_trybe', 'new_liked_trybe') AND s.object_id = t.id
LEFT JOIN
x_trybe_invites ti ON s.type IN ('new_join_trybe') AND s.object_id = ti.trybe_id AND s.postee_id = ti.to
LEFT JOIN
x_trybes_likes tl ON s.type IN ('new_liked_trybe') AND s.object_id = tl.trybe_id AND s.postee_id = tl.profile_id
LEFT JOIN
x_trybe_owner too ON s.type IN ('new_created_trybe') AND s.object_id = too.trybe_id
WHERE
s.user_id = '%s'
ORDER BY
s.registered DESC
I've ran both the queries and have captured images of the results of both queries.
Set A:
Set B:
How can I combine the two without the object_name returning NULL? If you have any questions please use the comments and I'll reply without hesitation.
Thanks in advance
I don't know about the rest of your query, but your case statement is incorrect. You have:
(CASE s.type
WHEN 'new_join_ambition' OR 'new_created_ambition' OR 'new_liked_ambition'
THEN a.name
ELSE 'a'
END) AS object_name
The ORs end up treating the values as numbers, so this is equivalent to WHEN 0 THEN . . ..
What you want is this form of the case:
(CASE WHEN s.type IN ('new_join_ambition', 'new_created_ambition', 'new_liked_ambition')
THEN a.name
ELSE 'a'
END) AS object_name
i need an sql stament that will give me something like this where if a field is null it doesn't do the join
SELECT AdminID,tblapartments.NameNo, tblgarages.GarageID, tblclients.Name FROM tbladmin,tblclients,tblgarages,tblapartments WHERE tblclients.ClientID =tbladmin.ClientID AND
IF (tbladmin.ApartmentID != null)
{
tblapartments.ApartmentID = tbladmin.ApartmentID
}
AND If(tbladmin.GarageID != Null)
{
tblgarges.GarageID = tbladmin.GarageID
}
Unless I'm missing something, this should just be an outer join.
SELECT
AdminID,
tblapartments.NameNo,
tblgarages.GarageID,
tblclients.Name
FROM
tbladmin INNER JOIN tblclients ON tbladmin.ClientID = tblclients.ClientID
LEFT OUTER JOIN tblgarages ON tbladmin.GarageID = tblgarages.GarageID
LEFT OUTER JOIN tblapartments ON tbladmin.ApartmentId = tblapartments.ApartmentID
You can use LEFT JOINs, when the joined column does not exist in the other table the result is a lot of NULL fields:
SELECT AdminID,tblapartments.NameNo, tblgarages.GarageID, tblclients.Name
FROM tbladmin
INNER JOIN tblclients
ON tbladmin.ClientID = tblclients.CliendID
LEFT JOIN tblgarages
ON tbladmin.GarageID = tblgarages.GarageID
LEFT JOIN tblapartments
ON tbladmin.ApartmentID = tblapartments.ApartmentID
I do not believe that this type of if logic is SQL standard. You could possibly implement it in a procedural SQL langauge like PL/SQL, plpgsql ... however to accomplish what you after i think a left join what you should look at.
SELECT AdminID,tblapartments.NameNo, tblgarages.GarageID, tblclients.Name
FROM tbladmin a
join tblclients b on b.ClientID = a.ClientID
left join tblapartments c on c.ApartmentID = a.ApartmentID
left join tblgarges d on d.GarageID = a.GarageID
After quick overview I didn't find how to deal with linq to sql if I have several nested inner joins.
That's what I'd like to have in linq
SELECT Booking.BookingId, Booking.EventId, Booking.StartDate, Event.Name, Person.FirstName
FROM Booking
INNER JOIN Event
INNER JOIN Asset
ON Asset.AssetId = Event.AssetId
INNER JOIN Person
ON Person.PersonId = Event.ContactPersonId
ON Event.EventId = Booking.EventId AND Event.State = 4
Does anyone know how to translate it to LINQ?
Thanks.
var q1= from a in booking,b in event,c in asset, d in person where a.eventid=b.eventid and b.state=4 and c.assetid = b.assetid and b.contactpersonid=d.personid select a,b,c,d
you can replace a,b,c,d at then with the column names you want
another way is to use the join keyword:
var w1= from a in booking join b in event on a.eventid equals b.eventid join c in asset on ...
var query = from b in context.Bookings
from e in context.Events
join a in context.Assets on e.AssetId equals a.AssetId
join p in context.People on e.ContactPersonId equals p.PersonId
where e.State == (byte)States.Approved && e.EventId == b.EventId
select new { EventName = e.Name, BookingDate = b.StartDate };