Oracle ODP.NET

I'm working now on a new project that in internals use ODP.NET - ORACLE Data Provider for .NET and latest Oracle 11g.

First of all I want to mention that ODP.NET is a great disappointment for me. In writing of very simple a stupid code ODP give me so many issues that I start to think that ORACLE completely loose own mind and release very unstable library for developers. I loose 2 days for fighting with found issues and I hope my article will help others a lot.

Simple Scenario that does not work in ODP.NET

Let's start from the simple scenario: Create typed DataSet with several tables, infill dataset by the data and update database by that data. Primary keys of the rows must be updated by Adapter automatically on Update method call.

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C# avionic instrument controls By Chootair
http://www.codeproject.com/KB/miscctrl/Avionic_Instruments.aspx



Статья интересна "расжованной" тематикой поворота картинок, ну и конечно самими контролами.
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Very often administrator in any company have to solve simple problem: delete from server old files. How we can do this?

1. Write command line script that will do this for us and run it periodically by windows scheduler service
2. write custom application that will do the same
3. find freeware or shareware with required functionality

In our case I want to introduce COMMAND LINE version of problem solving

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A Pure .NET Single Application Instance/Instancing Solution
http://www.codeproject.com/useritems/SingleInstancingWithIpc.asp

Интересное решение, позволяющее контролировать сколько инстансов запущенно, а также показывает, как сделать комуникацию между инстансами программ - передача данных между процессами. Построенно на Named Pipes + Mutex.
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Hierarchy data on DB layer

Simple ways

ParentId-to-ChildId

1. define primary key in table
2. define ParentRef column that has the same data type as primary key has and allowed NULL;

ID	Data	ParentRef
1	some data	NULL
2	node1	1
3	node11	2
4	node2	1

Pluses:

• easy to implement
• good structure where data accessed level by level;

Minuses:

• very complex queries for data extracting; implementation of query "extract node and all it childs" become very complex;

Separator

1. define separator that can not be used by user

ID	Name
1	ArtfulBits
2	ArtfulBits.Test
3	ArtfulBits.Test.Data
4	ArtfulBits.Samples

Pluses:

• easy to implement
• easy to extract node and it childs

Minuses:

• some times is very hard to define seprator
• growing of Name column value can become a problem if required deep hierarchy;

Combination

1. define primary key in table
2. define ParentRef column that has the same data type as primary key has and allowed NULL;
3. define special index column varchar()

ID	Name	ParentRef	Index
1	node1	NULL	NULL
2	node2	1	0001
33	node21	2	0001-0002
4	node211	33	0001-0002-0033
5	node22	2	0001-0002
99	nodeN	33	0001-0002-0033

Pluses:

• combination of performance and DB space usage
• easy to extract data in any suitable way

Minuses:

• required DB trigger on table for update and delete operations

Example

Separator is "/" char. Used 4 (four) chars for index key storage;