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QueryDSL Left Join with additional conditions in ON

Is it possible to do the following query in QueryDSL?
SELECT p.*
FROM parts_table p LEFT JOIN inventory_balance_table i ON
(p.part_no = i.part_no
AND i.month = MONTH(CURRENT_DATE)
AND i.year = YEAR(CURRENT_DATE));
Inventory balance stores inventory data for every part number/month/year; I need the only the data for the current year and month.
I've gotten the basic left join down:
QPartsTable qParts = QPartsTable.partsTable;
QInventoryBalance qBalance = QInventoryBalance.inventoryBalance;
JPAQuery q = new JPAQuery(em);
q.from(qParts).leftJoin(qParts.inventoryBalance, qBalance);
q.where(...);
List<Part> list = q.list(qParts);
which makes the correct sql, but only joining on the part number.
The resulting parts are checked for stock availability (among other things). The left join is necessary, because I still need parts that don't have an inventory entry yet (new parts for instance). Left join will get those without a matching inventory balance, but adding month = MONTH(CURRENT_DATE) and so on to where clause of the query removes the rows without an inventory balance (because they don't have year/month data).
For the same reason #Where and #Filter would remove those parts from the resulting parts list and are not applicable. Sadly #Filter and #Where are the only other results I'm getting with a search in Google and here on SO. (Oddly the Filter doesn't even affect the query even if filters are enabled in the session...)
The simplest solution would be my original question: How to turn the above SQL into QueryDSL? In general, is it possible to add more and/or custom conditions to the ON clause of the left join? What are the alternative solutions to this problem?
Thanks in advance!
Update - A follow-up question and an observation: (Perhaps this should be a new question entirely?)
After looking through the docs, it seems the older blogs demonstrating querydsl had the on() function for leftJoin's. Why is this no longer the case?
SQLQuery (or HibernateSQLQuery or some other variety) has the on() function, but leftJoin() accepts RelationalPath<T>, not an EntityPath<T> as JPAQuery does. It seems impossible to cast QClasses to a RelationalPath, so that's probably not the way to go...
Update 2 - We're using 2.9.0. Using on() gives an error, like it doesn't exist...

It is possible to use on() in QueryDSL, including the latest version. JPAQuery also supports on() predicate.
So this can be achieved,
QPartsTable qParts = QPartsTable.partsTable;
QInventoryBalance qBalance = QInventoryBalance.inventoryBalance;
JPAQuery q = new JPAQuery(em);
q.from(qParts).leftJoin(qParts.inventoryBalance, qBalance).on(qBalance.month.eq(yourMonth).and(qBalance.year.eq(yourYear))).list(qParts);
JPAQuery implements JPQLCommonQuery interface, so as others it has all necessary methods.
Here are docs from QueryDSL latest version with left join using on() example.
Update:
on() has been introduced since QueryDsl 3.0.0 version. So for versions below 3.0.0 it is not available.
I'd suggest to upgrade your version at least to 3.0.0, as the API is quite stronger comparing to old versions. Even more, I'd strongly advice to upgrade to the latest stable version (3.6.2), there shouldn't be any problems as new API supports everything as before, with additional features.
Update 2:
As #Cezille07 mentioned in the comment, there is a with() alternative for on(), in older versions. As we see from the issue , with() has been replaced with on() later on.
So for older versions with() does the trick. Here is a usefull link with more details.

ORDER BY with SUM, MIN, MAX, etc using Ebean

I am using PlayFramework 2.2.2 with Ebean and MsSql.
I am looking for the simplest or cleanest method to be able to sort by MIN or MAX etc.
A sample raw sql query might look like:
SELECT id, name, tickets FROM users WHERE tickets != NULL ORDER BY MAX(tickets)
I don't know if it's just me, but the documentation for ebean is incredibly confusing. It seems any time anyone comes up with a query that couldn't be written by a 9 year old, the answer is "switch to RawSQL". Well, why bother with Ebean at all then?
Anyway, I would really like to see some CONCRETE Ebean examples of ordering by MIN/MAX, etc.

Do you really need order by min ,max... since there is id in the select list.
Let me know whether id is unique or duplicates are allowed
Would suggest to use the following query incase the id is unique
select id,name,tickets from users where tickets is not null order by ticket desc

I encountered the same problem then I found the following information.
Design Goal:
This query language is NOT designed to be a replacement for SQL. It is designed to be a simple way to describe the "Object Graph" you want Ebean to build for you. Each find/fetch represents a node in that "Object Graph" which makes it easy to define for each node which properties you want to fetch.
Once you hit the limits of this language such as wanting aggregate functions (sum, average, min etc) or recursive queries etc you use SQL. Ebean's goal is to make it as easy as possible to use your own SQL to populate entity beans. Refer to RawSql .
-> http://www.avaje.org/static/javadoc/pub/com/avaje/ebean/Query.html

Sort the values by Date in mongodb

I am new to mongodb and I am trying to sort all my rows by date. I have records from mixed sources and I trying to sort it separately. I didn't update the dateCreated while writing into db for some records. Later I found and I added dateCreated to all my records in the db. Say I have total of 4000 records, first 1000 I don't have dateCreated. Latest 3000 has that column. Here I am trying to get the last Updated record using dateCreated column. Here is my code.
db.person.find({"source":"Naukri"}&{dateCreated:{$exists:true}}).sort({dateCreated: 1}).limit(10)
This code retruns me some results (from that 1000 records) where I can't see that dateCreated column at all. Moreover if I change (-1) here {dateCreated: -1} I am getting results from some other source, but not Naukri.
So I need help this cases,
How do I sort by dateCreated to get the latest updated record and by sources also.
I am using Java API to get the records from Mongo. I'd be grateful if someone helps me to find how I will use the same query with java also.
Hope my question is clear. Thanks in advance.

From the documentation you will (and you will, won't you - nod yes) read, you will find that the first argument to the find command you are using is what is called a query document. In this document you are specifying a list of fields and conditions, "comma" separated, which is the equivalent of an and condition in declarative syntax such as SQL.
The problem with your query is it was not valid, and did not match anything. The correct syntax would be as follows:
db.person.find({"source":"Naukri", dateCreated:{$exists:true}})
.sort({dateCreated: -1})
.limit(10)
So now this will filter by the value provided for "source" and where the "dateCreated" field exists, meaning it is there and it contains something.
I recommend looking at the links below, the first of the two concerned with structuring mongoDB queries and the find method and it's arguments. All of the functionality translates to every language implementation.
As for the Java API and how to use, there are different methods depending on which you are comfortable with. The API provides a BasicDBObject class which is more or less equivalent to the JSON document notation, and is sort of a hashmap concept. For something a bit more along the lines of the shell methods and a helper to be a little more like some of the dynamic languages approach, there is the QueryBuilder class which the last two links give example and information on. These allow chaining to make your query more readable.
There are many examples on Stack Overflow alone. I suggest you take a look.
http://docs.mongodb.org/manual/tutorial/query-documents/
http://docs.mongodb.org/manual/reference/method/db.collection.find/
How to do this MongoDB query using java?
http://api.mongodb.org/java/2.2/com/mongodb/QueryBuilder.html

Your query is not correct.Update it as follows :
db.person.find({"source":"Naukri", dateCreated:{$exists:true}}).sort({dateCreated: 1}).limit(10)
In Java, you can do it as follows :
Mongo mongo = ...
DB db = mongo.getDB("yourDbName");
DBCollection coll = db.getCollection("person");
DBObject query = new BasicDBObject();
query.put("source", "Naukri");
query.put("dateCreated", new BasicDBObject($exists : true));
DBCursor cur = coll.find(query).sort(new BasicDBObject("dateCreated", 1)).limit(10);
while(cur.hasNext()) {
DBObject obj = cur.next();
// Get data from the result object here
}

Java Persistence Criterias; Cast Expression<Timestamp> to Expression<Long>?

I am using the CriteriaBuilder and CriteriaQuery to build my query to the database, but I have encountered an issue that I do not know how to solve, since I am very new to this whole ordeal called JPA.
In Java, I have a property called timestamp for a class called Report, and it is set to the same corresponding #TemporalType.
I also have a class called Affiliate which has a list of Report objects.
In my query, I want to fetch all the Affiliate objects that do not have a Report in the last Affiliate.maxSilenceMinutes.
My questions:
Are there any ways in standardized JPA to modify dates? Like a CriteriaBuilder.subtractMilliseconds(Expression<Timestamp>, Long) of sorts?
If not, is there a way to cast Expression<Timestamp> to Expression<Long> so that I can subtract on a currentTimestamp literal to get the minimum value for a CriteriaBuilder.lessThanOrEqualTo(greatestReportTimestampMs, minimumAllowedMs)?
I know this might feel like a confusing question, but the main part is simply: Is it possible to go Expression<Timestamp> to Expression<Long>? It throws an exception for me if I try to use the .as(Long.class) method, but which should be the default underlying data type in most DBs anyway?
Hope you guys can help, since I feel kind of stuck :)

If you know the value you want to subtract at the time of querying,
you can subtract beforehand:
Calendar c = new Calendar();
c.setTime(timestamp.getTimestamp());
c.add(DAY, - someNumberOfDays); //or whatever unit you want
Date d = c.getTime();
If not, you probably need to call a database function to do the subtraction, via
CriteriaBuilder.function()
CriteriaBuilder.lessThanOrEqual() works on Comparables. Timestamps are comparable. So you could construct a Timestamp via new Timestamp(long ms)
and compare it with the other expression.
I hope this helps.

This is not built into Hibernate, so you will need a custom function of some kind.
The JDBC standard includes a function escape {fn TIMESTAMPADD( SQL_TSI_SECOND, secs, timestamp)} which should be translated into the correct SQL for the target database, but not all JDBC implementations provide it. There is therefore a chance you can add a custom StandardJDBCEscapeFunction to Hibernate's Dialect to get the result you need.
If you don't have that available, you'll have to find out what the correct database specific implementation is and there is a lot of variability here. For example:
Oracle: (timestamp + secs/86400)
SQLServer: DATEADD(ss,secs,timestamp)
DB2: (timestamp + secs SECONDS)
MySQL: DATE_ADD(timestamp, INTERVAL secs SECONDS)
Once you know it, you can use the correct expression as an SQL criteria.
The fact that date-time manipulation is not standardised in the Dialect and not fully implemented in many JDBCs means that what you are trying to do will be very difficult to write in a database neutral way.

Compare time part of datetime field in Hibernate

I've got an application that uses a hibernate(annotations)/mysql combination for ORM. In that application, I got an entity with a Date field. I'm looking for a way to select on that date within a time range (so hh:mm:ss without the date part).
In MySQL there's a function TIME(expression) that can extract the time part and use that in the where clause, but that does not seem to be available in Hibernate without switching to native queries. Is there an option in hibernate to do this, or should I loop through the results in java and do the comparison there? Would this be much slower as the MySQL solution, since that would not use indexes anyway?

The following functions are available in HQL, maybe you could use them:
second(...), minute(...), hour(...), day(...), month(...), year(...)

Add the expression as a SQL restriction rather than having a full native query. I don't know MySQL specifically, but imagine something like this:
Criteria criteria = session.createCriteria(MyTable.class);
criteria.add(
Expression.sql(
"TIME( {alias}.my_date, 'hh:mm:ss') >= :1",
dateRangeMin,
new StringType()
)
);