I need to figure out a way to get the index of every entry in a query result, let me show an example:
Suppose we have 3 entries in the Person table.
Willie
Mike
Alan
And I want to query that table to return all it's entries, and I want to know the index in which they are returned, with JPQL
A Pseudo code would be like this:
SELECT [INDEX], p.name FROM Person p ORDER BY p.name
What should I replace [INDEX] with to get a result like this:
1 - Alan
2 - Mike
3 - Willie
Is there a way to do that using JPQL?
You could probably use a database function and call it using FUNC() (EclipseLink) or FUNCTION() (JPA 2.1) from JPQL. EclipseLink also supports SQL() to embed any SQL you want inside JPQL. Or you could use a native query, or just add the index in Java code, since you really don't need to select it from the database.
Related
I have a mongo database and I'm trying to write an Eloquent code to change some fields before using them in WHERE or ORDER BY clauses. something like this SQL query:
Select ag.*, ht.*
from agency as ag inner join hotel as ht on ag.hotel_id = ht.id
Where ht.title = 'OrangeHotel'
-- or --
Select ag.*, ht.*
from agency as ag inner join hotel as ht on ag.hotel_id = ht.id
Order by ht.title
sometimes there is no other table and I just need to use calculated field in Where or Order By clause:
Select *
from agency
Where func(agency_admin) = 'testAdmin'
Select *
from agency
Order by func(agency_admin)
where func() is my custom function.
any suggestion?
and I have read Laravel 4/5, order by a foreign column for half of my problem, but I don't know how can I use it.
For the first query: mongodb only support "join" partially with the aggregation pipeline, which limits your aggregation in one collection. For "join"s between different collections/tables, just select from collections one by one, first the one containing the "where" field, then the one who should "join" with the former, and so on.
The second question just puzzled me for some minutes until I see this question and realized it's the same as your first question: sort the collection containing your sort field and retrive some data, then go to another.
For the 3rd question, this question should serve you well.
I have a custom query along these lines. I get the list of orderIds from outside. I have the entire order object list with me, so I can change the query in any way, if needed.
#Query("SELECT p FROM Person p INNER JOIN p.orders o WHERE o.orderId in :orderIds)")
public List<Person> findByOrderIds(#Param("orderIds") List<String> orderIds);
This query works fine, but sometimes it may have anywhere between 50-1000 entries in the orderIds list sent from outside function. So it becomes very slow, taking as much as 5-6 seconds which is not fast enough. My question is, is there a better, faster way to do this? When I googled, and on this site, I see we can use ANY, EXISTS: Postgresql: alternative to WHERE IN respective WHERE NOT IN or create a temporary table: https://dba.stackexchange.com/questions/12607/ways-to-speed-up-in-queries-under-postgresql or join this to VALUES clause: Alternative when IN clause is inputed A LOT of values (postgreSQL). All these answers are tailored towards direct SQL calls, nothing based on JPA. ANY keyword is not supported by spring-data. Not sure about creating temporary tables in custom queries. I think I can do it with native queries, but have not tried it. I am using spring-data + OpenJPA + PostgresSQL.
Can you please suggest a solution or give pointers? I apologize if I missed anything.
thanks,
Alice
You can use WHERE EXISTS instead of IN Clause in a native SQL Query as well as in HQL in JPA which results in a lot of performance benefits. Please see sample below
Sample JPA Query:
SELECT emp FROM Employee emp JOIN emp.projects p where NOT EXISTS (SELECT project from Project project where p = project AND project.status <> 'Active')
I'd like to write a Predicate which is calculated based on 2 columns.
for example - I have a daysBetween (int) and lastSent (date).
I'd like to know if there's a possibility to perform the following query :
select from X where the last_sent + [some other column which is interval] lessThan now()
something similar to (and I now this is not the correct way to write it..),
builder.between(userData.<Date>get("lastSent").addDays(userIntervals.<Integer>get("interval")),DateUtils.now());
Is there anyway of writing such a query using predicates?
JPA Criteria does not define an addDays() API. You can call a database specific function through the function() API,
See,
http://en.wikibooks.org/wiki/Java_Persistence/Criteria#Special_Operations
Some JPA providers provide extensions to JPQL and Criteria.
See,
http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Querying/Criteria#JpaCriteriaBuilder_and_EclipseLink_Extensions
and,
http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Querying/JPQL#EclipseLink_Extensions_.28EQL.29
I know how to use "DISTINCT" in Doctrine 2, but I really need to use "DISTINCT ON (field)" and I don't know how to do this with the QueryBuilder.
My SQL query looks like:
SELECT DISTINCT ON (currency) currency, amount FROM payments ORDER BY currency
And this query works perfect, but I can't use it with the QueryBuilder. Maybe I could write this query on some other way?
I would suggest that the SELECT DISTINCT ON (..) construct that PostgreSQL supports is outside the Object Relational Model (ORM) that is central to Doctrine. Or, perhaps put another way, because SELECT DISTINCT ON (..) is rare in SQL implementations Doctrine haven't coded for it.
Regardless of the actual logic for it not working, I would suggest you try Doctrine's "Native SQL". You need to map the results of your query to the ORM.
With NativeQuery you can execute native SELECT SQL statements and map
the results to Doctrine entities or any other result format supported
by Doctrine.
In order to make this mapping possible, you need to describe to
Doctrine what columns in the result map to which entity property. This
description is represented by a ResultSetMapping object.
With this feature you can map arbitrary SQL code to objects, such as
highly vendor-optimized SQL or stored-procedures.
SELECT DISTINCT ON (..) falls into vendor-optimized SQL I think, so using NativeQuery should allow you to access it.
Doctrine QueryBuilder has some limitations. Even if I didn't check if it's was possible with query builder, I do not hesitate to use DQL when I do not know how to write the query with query builder.
Check theses examples at
http://doctrine-orm.readthedocs.org/en/latest/reference/dql-doctrine-query-language.html#dql-select-examples
Hope this help.
INDEX BY can be used in DQL, allowing first result rows indexed by the defined string/int field to be overwritten by following ones with the same index:
SELECT
p.currency,
p.amount
FROM Namespace\To\Payments p INDEX BY p.currency
ORDER BY p.currency ASC
DQL - EBNF - INDEX BY
THere is a oracle query that I am trying to recreate using OpenJPA. I am writing a service in Websphere integration developer, and I am using OpenJPA as my ORM tool of choice. Previously this query was performed using a stored proc, a ref cursor was used and the information was retrieved like that. Now we are trying to use OpenJPA as our tool of choice. So I am thinking that I should then reconstruct the stored proc using OpenJPA...
SELECT DISTINCT
P.col1 as ID,
P.col2,
P.col3,
P.col4,
P.col5,
S.col6,
PC.col7,
P.col8,
A.ADDRESS_1,
A.ADDRESS_2,
A.ADDRESS_3,
A.CITY,
A.COUNTY,
A.STATE,
A.ZIP_CODE,
P.CONFIRMED_BY,
P.CONFIRMED_DATE,
P.MOD_USERID,
P.MOD_DATE
FROM EPCD13.PROVIDER P, EPCD13.provider_channel PC, EPCD13.provider_channel_link pcl,
EPCD13.provider_specialty ps, EPCD13.SPECIALTY S, EPCD13.Address A, EPCD13.ADDRESS_LINK AL
WHERE P.RESOURCE_ID = personID
AND P.RESOURCE_ID = PS.RESOURCE_ID (+)
AND 1 = PS.PRIMARY_SPECIALTY_ID (+)
AND PS.SPECIALTY_ID = S.SPECIALTY_ID (+)
AND P.RESOURCE_ID = PCL.RESOURCE_ID (+)
AND PCL.PROVIDER_CHANNEL_ID = PC.PROVIDER_CHANNEL_ID
AND 1 = PCL.PREFERENCE (+)
AND 9 = pc.channel_type_id (+)
AND PC.CHANNEL_ADDRESS NOT LIKE '%#%'
AND P.RESOURCE_ID = AL.RESOURCE_ID (+)
AND AL.ADDRESS_ID = A.ADDRESS_ID (+)
AND 1 = A.ADDRESS_TYPE_ID (+)
AND 1 = AL.PREFERENCE (+);
Notice all those inner Joins and so forth. I am thinking right now of putting a named query in one my methods that will return the same results as above. As you may note, there are multiple tables that are being called there and joined at various points... I am thinking I can just put this query into the createNamedQuery() function with minor changes... But I am thinking there has to be a simpler way to do this? Maybe not. Can I just call a stored proc using JPA?
Because your SQL is very complex it's not easy to convert to JPQL, I suggest preserve it.
You can use OpenJPA's NativeQuery, which can do SQL query. If your SQL is not started with SELECT, it will be treated as stored proc.
You can create a JPA entity for each table and then join the entities by doing something similar to this:
http://openjpa.apache.org/builds/1.1.1-SNAPSHOT/docs/jpa_overview_mapping_full.html
Look at the #OnetoMany and #ManytoOne and #ManytoMany annotations in the example for some ideas.