Hearing the Oracle

Home » Posts tagged 'SQL'

Tag Archives: SQL

De-duplicating Rows

dedup them!

dedup these hay-bogarting heffers for me!

Often the need arises to locate and remove duplicated rows, or partially duplicated rows from a table. Queries using the DISTINCT keyword (or it’s synonym UNIQUE) will retrieve and display rows without duplicates. But actually identifying and then removing the unwanted duplicates within a table represents a different level of work, and is also likely to involve greater resource consumption.     Continue…

Advertisements

Set Operators in SQL

150px-Edgar_F_Codd

E.F. ‘Ted’ Codd

Relational database design has strong roots within Set Theory, as can be seen in the seminal work of E.F. Codd more than 40 years ago. Most people recall encountering Venn diagrams during their school days, a pictorial excursion into this realm. Codd codified his relational ideals into a series of well-known rules, which represent an extreme case, not taking account of the often necessary pragmatic or performance reasons for selective denormalization. But his principles are still instructive and serve as a starting point for designing business schemas.     Continue…

Twisted Strings : Enforcing Password Strength

password TVgameIn this post, I aim to depict some practical utilizations of assorted Oracle string functions as an antidote to bland, often pointless examples given in SQL documentation. Security and reliable user authentication is ever in the news these days, and many studies confirm that most users continue to choose facile and predictable userids and/or passwords. This article summarizes recent user habits and hacker trends regarding passwords with some basic recommendations, while these two illustrate some of the most common (thus insecure) passwords.     Continue…

Pivot Queries : Then & Now

Back around the era of Oracle 6 or 7, I had an intuition that a certain type of query could be written within the limits of SQL*Plus syntax, but wasn’t quite clear as to how. I was doing some ad-hoc DBA work for a development database once a week or so, and wished to get a handle on who was doing what how frequently in terms of object creation. I envisioned a tabular matrix tallying kinds of objects by user with the aim of watching the changes over time. After doing some legwork exploring the sys.obj$ table and hitting upon using DECODE to trap specific object/user pairs into desired columns, I came up with this:     Continue…

R with Oracle

r1The data presentation graphic at right, and many of those sprinkled throughout this article (click them for better resolutions), are highlights from an enthusiast’s gallery which have been produced by the R statistical software package. R is an open-source programming language and environment which has gained much popularity among academics who want to apply statistical methods     Continue…