I have an ERP application running with Oracle forms and Oracle database. Now I am planning to migrate this application to a java based enterprise application. will it be a good idea to keep the existing oracle database as back end and developing a web application with certain level of changes/additions in the DB design.
There are two facts to know before answer your questions:
has your database schema some oracle forms special structures or is it in 3rd normal form and simply stores data using keys and enforced referential integrity?
How much stored code contains your database?
Ad 1. Oracle forms don't have specific schema reqiurements. They work best if your schema if based on 3rd normal form. If your schema is like this, use it for new Java application. We have both forms and Java EE applications on same database schemas and is works fine.
Advantage is, if you have keys (primary, unique, foreign) in your schema. Use them when generating Java app.
Probably you will have to add #Version columns for optimistic locking (see https://docs.oracle.com/javaee/6/api/javax/persistence/Version.html). But there is not reason to build new schema for it.
Ad 2. Your will have to overwrite bigger part of database stored code (triggers, procedures, functions) to Java. In most cases this does not have dramatic impact to schema structure, but deal with it.
So - if your database schema is not tailored to some UI client needs AND you want only use a new client, use your schema. If not, create a new one.
Related
I've been trying for days but cannot find the answer to this. I am using Oracle Application Express (APEX), someone else setup the initial connection to a "Apex" database in oracle, but I am trying to connect to our production database in oracle. I am making web forms and the web forms are connected to the "Apex" database that was setup already, but I need to connect to our production database so we can create reports from the data entered through the web forms. I need the tables to show up in the create page option from the production database, currently its coming from the apex database, please help.
Create Page View with Tables (from apex)
Thank You so much in Advance!
What is the "production database"? Is it really a different database (than the one you're currently connected to), or is it a user in the same database?
if former:
you could create a database link between those two databases and create synonyms for production users' tables in one of schemas your workspace is assigned to.
another option is to install Apex onto the production database, so that you could use current installation as "development" and then deploy the application into the "production-based" Apex
if latter, you might do the same (i.e. create synonyms, just without the database link), or simply assign the production schema to your workspace
You may be interested to read Mike's response to a question with a similar misunderstanding regarding architecture.
https://community.oracle.com/thread/4135843
Once you have your head wrapped around this, you can consider the parsing schema to your application. This schema defines the table access your application has, in the normal way Oracle handles table privileges.
Then it's up to you to define who has access to what pages, using APEX Authorisation Schemes.
The database I am using is Oracle 11g Express Edition release 2.
I created 2 schemas in the same instance xe. They all have the same tables names and sequences names and stored procedures and stored functions and views names. But the tables structures and views texts are different ( there is some modifications between them ).
The reason for the creation of these two schemas is because our project has two versions. So the first schema is used for the first version , and the second schema was created for the second version. The mechanism of our web application Spring project is that whenever a connection is made through the web application login page then a corresponding Oracle user is making a connection according to the login entered ; so there is no fixed credential connection , there are Oracle users corresponding to each web application login.
So in order for each user to work with each database objects then I created public synonyms for every objects , and granted permissions to them for each user. But the database objects are owned by the schema I mentioned at the beginning. Now my problem is this : our customer wants the two project versions to be run on a same instance ( same computer server ). So one of the project version cannot run because the public synonyms can only refer to a particular schema owner. So how to make the public synonyms work for each schema ?
In short, you can't. However, you can always use a distinct synonym name to identify the object.
Something similar to below:
create public synonym structures_v1 for schema1.structures;
create public synonym structures_v2 for schema2.structures;
Oracle provides 2 totally different technologies for this situation (which comes to my mind):
Editions (and Edition Based Redefinition)
PDBs
With Editions you can create the same Object once in each Edition - but there are limitations like tables are not editionable.
It's not a feature you just enable, you need to understand the concept and implement it properly.
PDBs enable consolidation of Databases with colliding namespace (such as your described synonyms) within the same CDB and therefore save SGA/memory. Basically they are totally separated - limited interference can be implemented when it's concept of object & data inheritance is understand.
What about creating a 3rd Schema and having Synonym and permission to query 1st and 2nd schema. Anyone tested this concept?
Let's imagine a standard situation.
Having the current DB schema in a working state, I would like to create a snapshot of this state of schema objects, name it SNAP_1.
Then if updated schema and got problems (bugs or unstable work of new code) it would be good to switch quickly - in one command - the whole schema code back to SNAP_1.
I'm wondering is there any built-in feature of Oracle DBMS for versioning:
PL/SQL code (schema objects)
Data (for example, within configuration tables)
Does Oracle DBMS give native tools for versioning at least one of these two?
The answer is no. But Oracle 11.2+ has something called "Editions".
This method has many restrictions. For example, data and table structure cannot be versioned.
Cool thing is that separate sessions can use a different version of the DB objects simultaneously. (package before fix and after fix)
Here is oracle's documentation.EDITION and
Examples of editions
We are developing a large data migration from Oracle DB (12c) to another system with SSIS. The developers are using a production copy database but the problem is that, due to the complexity of the data transformation, we have to do things in stages by preprocessing data into intermediate helper tables which are then used further downstream. The problem is that all developers are using the same database and screw each other up by running things simultaneously. Does Oracle DB offer anything in terms of developer sandboxing? We could build a mechanism to handle this (e.g. have dev ID in the helper tables, then query views that map to the dev), but I'd much rather use built-in functionality. Could I use Oracle Multitenant for this?
We ended up producing a master subset database of select schemas/tables through some fairly elaborate PL/SQL, then made several copies of this master schema so each dev has his/her own sandbox (as Alex suggested). We could have used Oracle Data Masking and Subsetting but it's too expensive. Another option for creating the subset database wouldn have been to use Jailer. I should note that we didn't have a need to mask any sensitive data.
Note. I would think this a fairly common problem so if new tools and solutions arise, please post them here as answers.
I have 2 databases, Oracle and SQlite. And I want to create exact copies of some of the Oracle tables in SQLite in one of my applications. Most of these tables contains more than 10,000 rows so copying each table by going through each row programmatically is not efficient. Also the table structure may change in the future so I want to achieve this using a generic way without hard-coding the SQL statements. Is there a any way to do this?
p.s. - This application is being developed using Qt framework. All the queries and databases are represented by QtSql module objects.
Can't help with Qt framework, but for large amounts of data is is usually better to use bulk-copy operations.
Export data from Oracle
http://download.oracle.com/docs/cd/B25329_01/doc/admin.102/b25107/impexp.htm#BCEGAFAB
Import data into SQLite
http://www.sqlite.org/cvstrac/wiki?p=ImportingFiles
IHTH
What you probably really want to use is the Oracle Database Mobile Server, which can automatically synchronize a SQLite and an Oracle Database.
The recent release of the Oracle Database Mobile Server (formally called Oracle Database Lite Mobile Server) supports synchronization between an Oracle Database and a SQLite or a Berkeley DB database running on the client. It supports both synchronous and asynchronous data exchange, as well as secure communications between client and server. You can configure the Mobile Server to synchronize based on several options without the need to modify the application that is accessing the database.
You can also find an excellent discussion forum for questions from developers and implementers using the Mobile Server.