Baur & King said in their book: Implicit joins are always directed along many-to-one or one-to-one association, never through a collection-valued association. [P 646, Ch 14] But when I am doing that in the code it is generating a CROSS JOIN instead of an INNER JOIN. Mapping is from Member2 (many-to-one) -…
Tag: database
Trying to get value out of a select option in the same form
I’m trying to get value out of the select option. But it doesn’t seems to be able to get since it’s on form. How do I do it ? I mean by having taking the value out of the option select. Answer 1.) You can not select all the items in a select with selected ! Without multiple=”multiple&#…
Can you have multiple transactions within one Hibernate Session?
Can you have multiple transactions within one Hibernate Session? I’m unclear if this is an allowable desirable. In my code I have a long running thread and takes items from a Blocking Queue, depending on what is on the queue, it may need to create and save a hibernate object, or it may not need to do an…
Android: Cannot perform this operation because the connection pool has been closed
I was reading through StackOverflow about this question and I still haven’t found a solution. I notice that sometimes, my app throws this error: I have a file called DatabaseHelper.java using this approach to get an instance of it: Then I have methods like this one (that it crashed in the line cursor.mo…
Hibernate SaveOrUpdate – multiple workthreads
While I have been able to find information on how Hibernate’s transaction work, so the database doesn’t corrupted, it has been harder to understand how Hibernate treats an object which is shared between threads, and each thread tries to save it to the database. This is my theoretical question: 1) …
Why do I need Transaction in Hibernate for read-only operations?
Why do I need Transaction in Hibernate for read-only operations? Does the following transaction put a lock in the DB? Example code to fetch from DB: Can I use session.close() instead of tx.commit()? Answer Transactions for reading might look indeed strange and often people don’t mark methods for transac…
How do insert a file like this into a MySQL Database
This the file I am trying to store in the database. I want to get the title and comments stored. I do get it in, but it stores only the first line. Please help, not really good with databases. Answer You first need to split line into Title and Comment and assign an id. Try this (note it is case
How to connect in java as SYS to Oracle?
I receive this error: How to fix? (I need to be SYS). Thanks. Answer try this :
H2 database error: Database may be already in use: “Locked by another process”
I am trying to use the H2 database from a Java application. I created the database and its tables through the H2 Console and then I try to connect from Java using However I receive the following error: Exception in thread “main” org.h2.jdbc.JdbcSQLException: Database may be already in use: “…
what databases can be used with java?
I am doing an undergrad final project, and need to justify my choice of MySQL for the database element of my project. Truth is, it’s the only one I can really use, and hence I went for it. What other database systems could I have used? Any advantages and disadvantages of these over MySQL? Answer In fact…