I have a JDBC application that uses Apache Derby. How can I migrate my entire database system to use MySQL?
I have 3 Java programs that access the database
I have 3 tables and 2 views
I am using Netbeans. I have never used MySQL before and do not know where to begin. Is there nice integration with Java and MySQL in Netbeans? How can I get nice integration with NetBeans and MySQL?
All help is greatly appreciated!
Looks like this plugin would probably help you:
http://netbeans.org/kb/docs/ide/mysql.html
I found this tutorial on the Spring site, but I think it is only a partial solution.
Tutorial
In it they are relying on hibernate to drop and create the tables, and I really don't like that. You have to go through special coding to add static data. For example, if your app is tracking devices, you probably want a table of device_types. At least some o those device types will be in the db, as well as devices, users, etc.
What I intend to do, is to use Derby until I am somewhat stable. From it, I will get the database schema and create it in mysql. It seems that the DB look utility can be used for that. DB Look
As added security I intend to run my web app with a db user that does not have the ability to add or drop tables. Also it is possible to remove the permission to delete rows if you use the concept of making rows "inactive" So instead of deleting a no longer used device type, you set the "active" flag to F. So your device type query would look like:
select * from device_type where active = 'T'
Related
I am trying to understand "changing database without changing code". Currently working with micro services using springboot, java, thymeleaf and cloud foundry.
I have a spring boot application and attached a database as a service using cloud foundry.
My problem is I am seeing that the purpose of micro service is allowing the ease to change services without changing code.
Here is where I got stuck
In java I have a sql script, "select * from ORDER where Status = 'ACCEPTED';"
Images source
My database would be attached as a service on cloud foundry using CUPS
"jdbc:oracle:thin:username/password//host:port/servicename"
So let say I want to change this database to CUSTOMER table(take it as a different database). This will throw an error because CUSTOMER table will not have "select * from ORDER where Status = 'ACCEPTED';"
I've changed database, but wouldn't I still have to go back to my code and change the sql script?
My Attempt to resolve this issue
So instead of hard coding my sql script in java "select * from ORDER where Status = 'ACCEPTED';"
I created a system environment variable and set it as sqlScript with value of select * from ORDER where Status = 'ACCEPTED'
Then in java I called the env variable String sqlScript= System.getenv("sqlScript");
So now instead of going back into java to change sql script, user can change it through environment variables.
this is a very dirty method to go around my issue, what would be a better alternative?
I know my logic of understanding is really wrong. Please guide me to the right path.
I think the phrase 'changing database without changing code' doesn't mean that if you add/remove fields in DB you do not have to modify your codebase - it just doesn't make any sense.
What it really means is that you should use good database abstractions, so in case you need to change your database vendor from, let's say, MYSQL to OracleDB your Java code should stay the same. The only thing that may differ is some configurations.
A good example of it is ORM like Hibernate. You write your java code once, no matter what is the SQL Database that you are using underneath. To switch databases the only thing that you need to change is a dialect configuration property (In reality it's not that easy to do, but probably easier than if we were coupled to a one specific DB).
Hibernate gives you a good abstraction over SQL databases. Nowadays we have a new trend - having the abstraction over different DB families like SQL and NoSQL. So in the ideal world, your codebase should stay unchanged even if you want to change MySQL to MongoDB or even Neo4j. Spring Data probably is the most popular framework that tries to solve this problem. Another framework that I found recently is Kundera but I haven't used it so far.
So answering your question - you do not need to keep your SQL queries as system variables. All you need to do is to use proper abstractions in your language of choice.
In my opinion, it would be better to use something like Flyway or Liquibase, which are integrated really well in Spring Boot. You can find more information here.
I prefer Liquibase, since it uses a higher level format to describe your database migrations, allowing you to switch databases quite easily. This way, you can also use different databases per environment, for example:
HSQLDB during local development
MySQL in DEV and TEST
Oracle in Production
It's also possible to export your current database schema from an existing database to have an initial version in Flyway or Liquibase, this will give you a good baseline for your scripts.
I read a lot of posts like:
querying embedded database in netbeans using derby
But still I'm having trouble to understand embedded databases.
1) I create a Derby database on Netbeans and I can create tables, link the database to a form and submit the data and update the records with no problem.
2) The problem arises when I want to make the program portable. I apply Clean and Build, then copy the dist folder and also copy the libraries, database, etc ... but when running the program does not recognize the database
3) I read in several places that it is appropriate that the database is created by code using something like
String host = "jdbc: derby: // localhost: 1527 / EmployeesCreateTrue; create = true"
and not creating the database on Netbeans Service...
If I do this procedure with code the database is created but it does not appear or does not allow me to connect from NetBeans and I wish I could fix it to create tables from NetBeans and not from code.
4) I read manuals "how to import a database from Derby to NetBeans" and it doesn't work...
Question: What is the best way to create a database, tables and connect to NetBeans for the final application to be easily portable?
1) Create the database on Netbeans with the wizzard?
or
2) Just plain code on the application?
I don't understand precisely what you mean by "the database is created but it does not appear."
I think if you were to explain that precisely, the community could probably help you.
There are three common reasons for "table does not exist" when you think you've created the tables; I've explained those cases in this answer: Is it necessary to create tables each time you connect the derby database?
Please let us know more information about your situation so that we can help you better understand the behavior of your application.
I'm not 100% sure if this is your problem, but a lot of problems people seem to have with Netbeans and Derby seems to come from the fact that they don't set derby.system.home explicitly. When you don't, Derby stores databases in the current directory, and that is likely different when working in the IDE, either in the Services tab, or your own code, than when you execute your app's jar as a standalone program. So the advice (which you will also find in the manual) is: always set derby.system.home. An alternative would be to use full paths to the databases, but that rarely works well for a real application that is deployed on different machines.
I had the same problem --had the derby db in the services but the netbeans coded programs didn't access it. I solved it by adding the derby database (copy paste) to the package in the Files section. I use Windows 7. Once I did that, I was able use multiple tables (before netbeans just ignored secondary tables and only allowed me to use the primary table).
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Closed 10 years ago.
I'm working in postgresql database with jsp/servlets, I need to connect the external jdbc such as MySQL,MS SQL,PostgreSQL and migrate all the datas to my Postgresql database.
Can any one please point me in the right direction?
I believe there is no simple solution for your task, unless its a fairly basic project.
In real world sometimes we're forced to use db specific definitions like indices, transaction management, sequences, etc. I'm not telling about db specific queries or things like PL/SQL or Transact SQL that simply are not supported by all the data bases.
If you're using Hibernate/JPA, and in particular schema generation from your entities, you can try to connect to the old schema, fetch all the entities and serialize them on your hard drive, than configure datasource with the new db address and try to deploy the entities there but in general I wouldn't expect that all will be clear and work out of the box
Disclamer, I'm a Java guy, so I share my thoughts from the perspective of java developer and not a DBA :)
Hope this helps
As RC said in the comments, try using Talend they have a open studio Here is the link. Free version is absolutely fine with your case. You can write (or design) a job and export it as a jar and use it part of your application or run it as cron scheduler based on your requirement.
They have some tutorials over the web and some on youtube also. They should be helpful.
This explains how to connect to PostgreSQL with JDBC. Does that help?
I need SQL functionalities for a Java JSE application, but dont need a whole SQL server, with things like listen on a port, connection string or even a standalone process to be runned or configured.
I also would prefer to work with files as storages, so that file path identifies DB data.
So given to the DB API the name of a file, I would need perform SQL with the file as DB storage, supporting tables, search, joins and inserts, without thinking to things like ports, external processes, server installation, ecc..
Without any other configurration action, since any other configurable feature is not needed.
Is there some library, preferrably installable as single .jar, that provides this functionality?
If there is not this library, which file-based DB is the simplest to configure and use within JSE, and which configuration steps are needed to perform a query in the provided DB and deploy it with (working) the java .jar application?
I suggest Derby db.apache.org/derby/
I like H2 Database very much. It compares very well with other database engines.
Sure, Hypersonic SQL or Derby, the database that comes bundled with Java 7, will both fill the bill. SQLite would be a third alternative.
you may want to check this out:
http://www.sqlite.org/
I have used HSQLDB in the past and liked it. Depending on what your needs are, you might also be interested in JoSQL which allows you to do SQL type of queries on java collections.
Is there a database out there that I can use for a really basic project that stores the schema in terms of documents representing an individual database table?
For example, if I have a schema made up of 5 tables (one, two, three, four and five), then the database would be made up of 5 documents in some sort of "simple" encoding (e.g. json, xml etc)
I'm writing a Java based app so I would need it to have a JDBC driver for this sort of database if one exists.
CouchDB and you can use it with java
dbslayer is also light weight with MySQL adapter. I guess, this will make life a little easy.
I haven't used it for a bit, but HyperSQL has worked well in the past, and it's quite quick to set up:
"... offers a small, fast multithreaded and transactional database engine which offers in-memory and disk-based tables and supports embedded and server modes."
CouchDB works well (#zengr). You may also want to look at MongoDB.
Comparing Mongo DB and Couch DB
Java Tutorial - MongoDB
Also check http://jackrabbit.apache.org/ , not quite a DB but should also work.