At the moment, I have a little JavaFX app that generates reports and statistics from the data on a remote MySQL-Server. I use EclipseLink for persistence. Since the access is read-only and the data doesn´t always need to be fresh, I thought I could speed things up by using an embedded DB (H2) that can be synchronized to the remote server when and if the user wishes to. The problem is, I don´t have a clue how to go about it.
What I came up with so far, is to execute mysqldump, make a dump of the remote server and execute the resulting SQL script locally. This is surely far from elegant, so: Is there a patent solution for this task?
Well, 50 tables possible have a considerable amount of relations, this can be tricky... As far as I know there is nothing that automate this for you or something like that. Very possible that you will have to create your own logic to that. When I did something like what are you trying to do I used the logic of "last update", like, the local data have the timestamp of the time it was last synced with the remote, and the remote data have the timestamp of the last time the data was updated there (himself on the table, or even a relation to it like a One-To-One). Having that data, every time the local user enter a part of the system that can be outdated, the client connect to the server and check if the last update timestamp is bigger that the local synced timestamp, if so, it updates the full object and relation. I consumed some time to develop but at the end worked like a charm. There may be some other way to do it, but this was the way I found at the time. Hope it helps you with your problem.
I'm trying to map some Java classes using the Hibernate JPA implementation. My problem is that I can't use hardcoded Strings als column namens. You can see the error message I get in the picture below.
I'm using OpenJPA as my Default JPA Provider and have already tried to change it.
IntelliJ Version 14.0.3
regards,
You have to associate your data source (create a data source in database view first - aka your real JDBC database connection) with a persistence unit or session factory (hibernate.cfg.xml).
Follow below steps and the warnings will disappear:
Open the Persistence tool window (View | Tool Windows |
Persistence).
Right-click the necessary module, persistence unit or
session factory, and select Assign Data Sources in the context menu.
In the Assign Data Sources dialog that opens, click the Data Source
field and select the necessary data source. (To remove the
association with the data source, select none.)
See here: Associating data sources with session factories and persistence units
For those who just want to disable this check, go to
Intellij IDEA -> Preferences -> Search "Unresolved database references in annotations" and uncheck it.
(macOS Mojave and Intellij Ultimate 2019.3)
This will disable the inspection and remove all the "Cannot resolve column…" errors on the #Column annotations. Intellij will stop checking if the String column names exist in the database tables. Do it at your own risk.
I found Panos' answer useful, but I didn't see anybody mention adding the database as a data source. Perhaps that's routine enough to be assumed, but if not, here's what I had to do:
Select View/Tool Windows/Database
The Database window usually appears on the top right.
In the Database window, click the green + sign and select Data Source/MySQL (or whatever flavor of Data Source you're using).
The Data Sources and Drivers window pops up.
If your database isn't listed there, use the empty form to add the following:
Host: usually localhost, but if your test database is living
on another machine, put that address in.
Username: for your database use.
Password: for your database user's password.
IDEA might need some fiddling to find the JDBC driver. I was told that in theory it should have found it in the maven build process for the project I was working on, but it did not. I reopened View/Tool Windows/Database and looked at my MySQL entry. At the bottom it had an error message next to Driver:, and also a MySQL link. I clicked the MySQL link and IDEA brought up a popup to fetch Connector/J.
Despite the fact that the checkboxes for Auto commit and Auto sync defaulted to checked and I left them that way, IDEA seemed to need a nudge. Or perhaps it was just taking a while and I was impatient.
In any event, first I double-clicked on the line for my database in Database. That seemed to do it, but I didn't realize I needed Persistence yet, and while sorting that out, at a coworker's suggestion, I also clicked the Synchronize button (two arrows in a circle) on Database.
You can also right-click on your database in Database and select Synchronize.
It may take a few seconds, but you should see IDEA filling in the database schema under the entry in Database.
Finally I found Panos's answer and fixed Persistence.
Select View/Tool Windows/Persistence
The Persistence window usually appears on the top left.
In the Persistence window, right-click on your project and select Assign Data Sources.
IDEA pops up a dialog with two columns, your project in the left column and in my case an empty cell in the right column. Click on the empty cell and IDEA should give you a dropdown that allows you to select the database you just added.
Again, it may take a few seconds for IDEA to finish analyzing the data source and redo all the inspections.
Just for anyone else whom this didn't solve and comes across via google (like myself) .. setting the table name via the #Table Annotation fixed it for me.
Actually this is not any error that prevents your code to compile. Probably your spell-checker is on and which gives you the spelling mistake. If you can compile your code then you may ignore these type of scenario.
Look you have not getting any error for other text like #Column, #GeneratedValue etc. That means jars using these kind of stuff are in your build path. So I think you can ignore these type of error.
maybe this solution also help someone...
Open Database dialog window from the right side of Intellij
Go to DB Data Source Properties (find it in top menu)
Go to Schemas
Uncheck "Default database"
Check your specific DB and inside also check Default schema(public)
Good luck!
If you are using the JPA, it is also important to set up the SQL Dialect as
HSQLDB instead of MySQL. This is often confusing because it feels like MySQL is the correct dialect, but in fact what you are dealing with hibernate is HSQL.
If you have just upgraded to IntelliJ 2017.13 or other derivatives of this version (e.g., Webstorm), or you've just re-imported your project, it might mess up the language injection and need to manually correct this.
This can be accomplished via the Project
Settings -> Languages and Frameworks
part of the IDE.
If there is no real mismatch and this warning happens just because of IDE, you can easily link your project with the data source that you connect. Intellij already suggests the way to do it.
I'm using Intellij and connecting DB by JPA. I've met problem just like you and this is my solution.
You need to connect your database following these steps:
View -> Tool Windows -> Database -> then add database you are using to Intellj
After connect your database, you need to assign data source to Intellj by following these
View -> Tool Windows -> Persistence -> then add data from database you just added from 1 step
OK. That's all!
P/s: make sure your code work well!
I've got a rather large program that interacts with a MySQL database. I recently changed the structure of the database considerably, but I thought I had made all of the necessary changes to my program to compensate for those database changes, but clearly I haven't.
I just recently several error messages, the first of which is this:
java.sql.SQLException: Value '0000-00-00 00:00:00' can not be represented as java.sql.Timestamp
Strangely, though, it doesn't give tell me in which file this error came from (as a typical stacktrace would), let alone on which line number. How can I figure out from where this is coming?
I have a lot of calls to the database in this program, most of which deal with a Timestamp column. And I'm afraid that, while I have been using Eclipse for months now, I still have yet to use its Debug perspective. How can I use that?
I have a web application based on Java EE and MYSQL.
The problem which I am facing right now is, there is an event getting fired online, which is updating a table entry for a large number of rows.
There is also a batch job scheduled in the environment, say for every 6 minutes, which is also updating the same table entry, as mentioned above.
So the situation is that, when the online event is getting fired in the time range of the batch run, the table is getting locked.
So, experts please provide your ideas, on how to prevent the lock to take place.
Looks like a design issue,take a look at using temporary tables.
I am using hibernate in my java dynamic project and since last week I am getting one exception called "No row with the given identifier exist[#entity(0)]. I found same problem asked earlier and I did same as suggested but problem persisted. I tried using "not-found=ignore" case as well but it doesn't work. Even the project is working fine # Production but here # development is quite disturbing. Please help me.
Maybe this can help explain it.
Just a suggestion: whenever I get an error message of any kind, I immediately cut & paste it into a Google search to see what comes back. It's highly unlikely that I'm the first person to encounter a problem.