Hierarchical Queries in Oracle

Hierarchical Queries: A QuickStart Guide

A hierarchical query is one that works on data with a "tree" relationship. An Example of Hierarchical Data The employee-manager relationship in SCOTT’s famous EMP table. Each employee record has a manager’s id associated with it. In effect, there is a "tree" of data relationships At each level, I can get the employee-manager relationship as […]

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Oracle Interview Tips

7 Surefire Tips to Ace your Interview

Presenting for you the third article in the series on interviews. Earlier in the series: tips to make your resume stand out, and the fallacy of memorizing interview questions. Your resume has made it to the shortlist and you’ve got that precious interview call. You’re excited and nervous and eager to sail through. How can […]

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How to Create an Awesome Résumé

How to Create an Awesome Résumé: Eight Golden Rules

We’ve seen the pointlessness of memorizing answers to interview questions, earlier in the series on interviews. In this article, we have for you 8 gleaming tips to give your résumé a facelift and get you that valuable interview call. Your résumé is your sales pitch, your chance to make an impact in the brief time […]

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Interview Questions

The Fallacy of Interview Questions

A series of posts about Oracle interviews starts with this article. “Interview Questions” is a hot topic on many Oracle forums. Job aspirants want these questions to be listed down, emailed to them, complete with model answers. Some imagine that by learning answers to such questions, they will land a job, though they have not […]

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delete-truncate-drop

The Difference between DELETE, TRUNCATE and DROP

DELETE, TRUNCATE and DROP – all three commands get rid of table data. How exactly are they different? When should you use which? A bird’s eye view of their differences, a table comparing the three.

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Top N Query in Oracle

Nth Highest Salary in Oracle

“How can I select the Nth highest salary of the EMP table?” This is a question that every Oracle newbie stumbles over. Ask it on a forum and you’re pointed to the archives. That gets you nowhere as when you search the archives, all you find is a host of other messages also asking you […]

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Validate Email Address in SQL

How to Validate Email Address in SQL

In applications that take user email id as input, there is a need to check for email id validity. Here is a very easy validation for syntax of an email address, using regular expressions in Oracle SQL. The basic email address format is username@example.com. The SQL will verify that the email address provided fits into […]

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Regular Expressions in Oracle

Regular Expressions in Oracle Made Easy

What is a regular expression? A regular expression (also called regex or regexp for short) is a sequence of characters that describes a pattern in text. Some examples of regular expressions: p..t => A dot stands for a single character. This regular expression will match words that start with a ‘p’, end with a ‘t’ […]

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WHEN OTHERS THEN NULL

WHEN OTHERS THEN NULL

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Why Should You Use PL/SQL Packages

6 Reasons Why You Should Use PL/SQL Packages

A package is: …a database object that groups together logically related procedures/functions, and other constructs like variables, constants, PL/SQL types, cursors, and exceptions. One may well ask: when it’s possible to write standalone procedures/functions and define related variables within them, why have packages at all?

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