50 Shades of Oracle Database Certification Exam

In this article, I would like to talk about one of the basic certifications from Oracle – Oracle Database SQL Certified Expert. Unfortunately, this certification has become unavailable recently, but still, this article may be useful for preparing for other certifications and exams from Oracle. I wish a good read to everyone who wants to know which questions and tricks may await them and wants to be ahead of the game. (more…)

Tricky Questions about C#

Some questions may seem too basic, but they still contain tiny tricks. Sometimes even a simple question may nail to the wall. These questions will be useful to all who study the language.

So, let’s start!

1. What will be the result of execution of the following code?

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Preparing for Exam 70-483: Programming in C#

During preparation for exam 70-483, I found lots of websites containing links to various manuals that helped me a lot. But what really helped me was the memo notes I composed for myself and which I’d like to share in this article. I do not target to provide a detailed description of C#, I just want to refresh your memory and to highlight certain aspects of C#. If you are not familiar with some aspects, it means you have gaps in your knowledge that should be eliminated. (more…)

Tips for Read/Write Locks Depending on Transaction Isolation Level in MSSQL

Read Uncommitted

  • If data is being changed in one transaction, selection of this data (in other transaction or without a transaction) will not wait till the first transaction is finished and will return data entries of uncommitted transactions.
  • If data is being read in one transaction, updates of this data in other transaction will not wait till the first transaction is finished.
  • Shared locks are not used. Identical to setting the NOLOCK hint for all selections in Read Committed.
  • Exclusive locks are enabled during statement execution and disabled at the end of the transaction.

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XML performance tips

Parsing data from XML using XQuery is a routine practice. In order to do this most effectively, little effort is required.

Suppose we need to parse data from the disk file with the following structure:

Use BULK INSERT, if you need to read data from a file:

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Retrieving SQL Server Metadata with Help of T-SQL

This article contains a list of scripts that mine the SQL Server metadata in the various system functions, stored procedures, tables, and catalog views. Metadata queries are really helpful in discovering information for a given database schema. You can copy all the T-SQL scripts that are listed in this article and use for your own purposes. However, please do some tests before apply to a production database.

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