I have a record that I need to do some validation on. This record can potentially have multiple children. I need to create a collection (I was planning on using a standard list) containing the ID of every child record but this needs to be recursive (i.e. each child record can also have child records of its own, and I need each of those IDs as well, ad infinitem).I'm using MSSQL Server for my DB but I'm not too sure how I would structure the necessary SQL query.
This is what I have tried;
DECLARE #Id VARCHAR(30) = '[Record Id]';
WITH cte AS
(
SELECT record.id, record.parentid
FROM records r
WHERE id = #Id
UNION ALL
SELECT record.id, wo.parentid
FROM records r JOIN cte c ON wo.parentid = c.id
)
SELECT id
FROM cte;
I get the following error:
The statement terminated. The maximum recursion 100 has been exhausted before statement completion.
Related
I have a JPQL subquery in which I want to return a list of customerIds that meet a specific condition based on a ManyToOne relationship as shown below:
SELECT c.customerId
FROM Customer c
INNER JOIN FETCH c.customersChild cc
LEFT JOIN FETCH c.childsPet cp on cp.name = 'Rover'
GROUP BY c.customerId
HAVING (COUNT(cp.name) / COUNT(*)) = 1
In this case, the customer should only be present in the list if all of their childrens' pet's names are Rover. The HAVING (COUNT(cp.name) / COUNT(*)) = 1 clause works as-is in Oracle (SQL), since COUNT(cp.name) counts the number of non-null rows for each customer, and COUNT(*) counts the total number of rows (including nulls present due to the left join) for each customer... I believe COUNT(cp.name) works in JPQL but it doesn't seem like there is equivalent for COUNT(*)... does anyone know if there is a way to count all the rows within a group including nulls?
I would suggest you rewrite your query to the more understandable anti-join variant:
SELECT c.customerId
FROM Customer c
WHERE NOT EXISTS (
SELECT 1
FROM c.customersChild cc
JOIN cc.childsPet cp
WHERE cp.name = 'Rover'
)
I have an update/insert SQL query that I created using a MERGE statement. Using either JdbcTemplate or NamedParameterJdbcTemplate, does Spring provide a method that I can use to update a single record, as opposed to a Batch Update?
Since this query will be used to persist data from a queue via a JMS listener, I'm only dequeuing one record at a time, and don't have need for the overhead of a batch update.
If a batch is the only way to do it through Spring JDBC, that's fine... I just want to make certain I'm not missing something simpler.
You can use a SQL MERGE statment using only a one row query containing your parameters.
For example if you have a table COMPANYcontaing IDas a key and NAMEas an attribute, the MERGE statement would be:
merge into company c
using (select ? id, ? name from dual) d
on (c.id = d.id)
when matched then update
set c.name = d.name
when not matched then insert (c.id, c.name)
values(d.id, d.name)
If your target table contains the parametrised key, the name will be updated, otherwise a new record will be inserted.
With JDBCTemplate you use the update method to call the MERGEstatement, as illustrated below (using Groovy script)
def id = 1
def name = 'NewName'
String mergeStmt = """merge into company c
using (select ? id, ? name from dual) d
on (c.id = d.id)
when matched then update
set c.name = d.name
when not matched then insert (c.id, c.name)
values(d.id, d.name)""";
def updCnt = jdbcTemplate.update(mergeStmt, id, name);
println "merging ${id}, name ${name}, merged rows ${updCnt}"
Just use one of update methods, for example this one: JdbcTemplate#update instead of BatchUpdate.
Update updates a single record, batchUpdate updates multiple records using JDBC batch
In my Java Web application I use Postgresql and some data tables are filled automatically in server. In the database I have a STATUS table like below:
I want to select the data related to a vehicle between selected dates and where the vehicle stayed connected. Simply I want to select the data which are green in the above table which means I exactly want the data when firstly io1=true and the data when io1=false after the last io1=true. I have postgresql query statement which exactly gives me the desired data; however, I have to convert it to HQL because of my application logic.
working postgresql query:
WITH cte AS
( SELECT iostatusid, mtstrackid, io1,io2,io3, gpsdate,
(io1 <> LAG(io1) OVER (PARTITION BY mtstrackid
ORDER BY gpsdate)
) AS status_changed
FROM iostatus
WHERE mtstrackid = 'redcar' AND gpsdate between '2014-02-28 00:00:00' and '2014-02-28 23:59:59'
)
SELECT iostatusId, mtstrackid, io1, io2, io3,gpsdate
FROM cte
WHERE status_changed
OR io1 AND status_changed IS NULL
ORDER BY gpsdate ;
How should I convert the above query to HQL or how could I retrieve the desired data with HQL?
The goal of hibernate is mapping database entities to java objects. This kind of complex queries are not entities themselves. This is against the spirit of hibernate.
If this query generates an entity in your application logic, I recommend putting the results into a table and applying Hibernate queries to that table.
If this query generates some kind of aggregation or summary, there are two possible ways:
One way is you compute this aggregation/summary in your application after retrieving entities from iostatus table with hibernate.
If this query has nothing to do with your application logic then you can use Native SQL interface of Hibernate and execute the query directly. (You can even use JPA if you are willing to manipulate two database connections.)
If you absolutely need to convert it to HQL, you need to eliminate the partition function. If the order of iostatusId is identical to the order of gpsdate, you can do it similar to
SELECT i2.*
FROM iostatus i1
INNER JOIN iostatus i2 ON i1.iostatusId = i2.iostatusId - 1
AND i1.io1 <> i2.io1
AND i1.mstrackid = i2.mstrackid
WHERE i2.mtstrackid = 'redcar' AND
i2.gpsdate between '2014-02-28 00:00:00' and '2014-02-28 23:59:59'
If gpsdate is no way related to iostatusId then you need something like
SELECT i2.*
FROM iostatus i1
INNER JOIN iostatus i2 ON i1.gpsdate < i2.gpsdate
AND i1.io1 <> i2.io1
AND i1.mstrackid = i2.mstrackid
WHERE i2.mtstrackid = 'redcar' AND
i2.gpsdate between '2014-02-28 00:00:00' and '2014-02-28 23:59:59' AND
NOT EXISTS (SELECT * FROM iostatus i3
WHERE i3.gpsdate > i1.gpsdate AND
i2.gpsdate > i3.gpsdate AND
i3.io1 = i1.io1 AND
i1.mstrackid = i3.mstrackid)
I guess both of the queries can be converted to HQL, but I'm not positively sure.
By the way I must warn you that, these methods might not perform better then finding the changes in your application, because they involve joining the table onto itself, which is an expensive operation; and the second query involves a nested query after the join, which is also quite expensive.
I am fetching records from my "record" table. "record" table has many columns tow of which are
client_id, foreign key mapping to client table.
creation_date , date of record creation
I would like to do a query on this table , but I would like to fetch only one record per client(latest creation_date record has preference).
Will following work?
select r.id,r.xx,r.yy
group by(r.client_id),r.creation_date
from record r
order by creation_date desc
I tried above and seems records fetched are not of latest creation dates.
Hope my question is clear
Just keep your query and add a WHERE condition :
SELECT r.id,r.xx,r.yy
GROUP BY(r.client_id)
FROM record r
WHERE r.creation_date = (SELECT MAX(creation_date) FROM record tmp WHERE tmp.client_id = r.client_id )
Take a look at This discussion
This should give you a good starting point in HQL.
from Record as r inner join fetch r.client
where r.creation_date > (
select max(rec.creation_date) from Record rec
where rec.client.client_id = r.client.client_id
)
This of course assumes that your Record has a reference to its parent Client called client.
I have a query like the following:
Select new mypackage.MyClass( u, max(sc.serviceDate))
from Unit u left join u.serviceCalls sc
where u.organization.key = :organizationKey
So, my mapping is that I have a Unit, which has a collection of ServiceCalls (FetchType.LAZY), and also has an organization. Each ServiceCall has a serviceDate.
In my query, I would like to select the entire Unit, but not all of the serviceCalls. I would like to fetch the most recent serviceDate if one exists.
Attempting to execute the query through eclipselink on postgres gets me the following (I removed some selected fields from the query output)
Internal Exception: org.postgresql.util.PSQLException: ERROR: column "t0.key" must appear in the GROUP BY clause or be used in an aggregate function
Position: 8
Error Code: 0
Call: SELECT t0.KEY, MAX(t1.service_date) FROM unit t0 LEFT OUTER JOIN service_call t1 ON (t1.unit_key = t0.KEY), organization t2 WHERE ((t2.KEY = ?) AND (t2.KEY = t0.organization_key))
It looks like max is being applied across all service calls instead of getting me the max for each unit. Is there a way to do this or am I going to have to just getch all the service calls and get the max that way?
Do you need a group by u at the end?