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Write Smarter Queries with the SQL WITH Clause

SQL WITH clause, or the subquery factoring clause, makes queries more efficient and readable. When a subquery is being processed multiple times, WITH lets you factor it out, give it a name and then reference the name wherever needed in the query.

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ORA-06592: CASE_NOT_FOUND Exception

Though CASE behaves like IF-THEN-ELSE, it differs in one important way – CASE requires a defined leg for each scenario. If an undefined leg is chosen, the exception ORA-06592: CASE not found while executing CASE statement is raised.

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Simple CASE vs. Searched CASE

The CASE construct in Oracle has two variants – the simple CASE and the searched CASE. Here’s a closer look to compare them in structure and functionality.

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The Difference Between DECODE and CASE

Both DECODE and CASE statements in Oracle are used for IF-THEN-ELSE conditional operations, but there are distinct differences in their power and behavior.

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Selecting ODD or EVEN rows from a table

Question: How can I select only the even/odd rows from an Oracle table? Answer: Talking of “even or odd rows” is meaningless in Oracle until you have ordered the rows.

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LEVEL Pseudocolumn in Hierarchical Queries

LEVEL is a pseudocolumn (i.e. not a real column in the database but available in a query), which has a special function in hierarchical queries – it returns the position of any row in the hierarchy.

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Hierarchical Queries: A QuickStart Guide

A hierarchical query is one that works on data with a tree relationship. Oracle provides specialized keywords that work with hierarchical queries, such as START WITH…CONNECT BY, PRIOR and SYS_CONNECT_BY_PATH.

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7 Surefire Tips to Ace your Interview

To make a success of a job interview, you have to start hitting the right notes from before the interview. Here are a few interview tips for you.

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How to Create an Awesome Resume: 8 Golden Rules

Your resume is your sales pitch. Make it stand out with these 8 gleaming resume tips, make it get you that valuable job interview call.

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The Fallacy of Interview Questions

When you are starting out preparing for Oracle interviews, you might imagine that learning answers to lists of interview questions is the way to get a decent job. This article shows you why this is the wrong way to go about it, and suggests what to do instead.

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