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Channel: René Nyffenegger on Oracle
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On tracking data changes in a table

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On storing objects in tables

In this article, I want to demonstrate how to achieve a parent-child relationship with PL/SQL objects stored in tables.

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On emulating callback functions through deriving an object from another in...

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On max and group by

This article presents three different ways to group a select's result set and find each group's record whose column is max().

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On an integer not always being an integer

Until recently, I believed that an integer is a number that can only store whole numbers. Unfortunately, that is not always the case with Oracle.

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On a member function calling a member procedure

I was very surprised when I tried to call a member procedure from a member function because I got a PLS-00363: expression 'SELF' cannot be used as an assignment. Why this is and how to avoid this.

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On solving a sudoku with Oracle

A is a puzzle that consists of a 9x9 grid whose cells contain numbers between 1 and 9. At the beginning, only a few of these celles are filled in, and it's the solver's task to fill in every cell...

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On using dbms_utility.name_resolve

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On the missing product() aggregate function

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On a better describe

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On generating ERDs with desc_table and neato

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On storing hierachical data

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On using triggers to keep summary data in the nodes of hierachical data in sync

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On eliminating outliers in avg() queries

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On improving a better describe

Recently, I presented . Now, sent me an email with some improvements.

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On mixing outer joins with inner joins

A few ways to combine an outer joins with an inner join in a select statement.

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On reading blobs from and writing blobs to a file

Writing blobs to a file and reading them from a file is too tedious for my liking. Therefore, I have written a package to faciliate these tasks. It comes with a procedure (to_file) which writes a blob...

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On creating bitmaps with pure PL/SQL

Out of idle curiosity, I wanted to know if it is possible to create bitmaps (BMPs) with pure PL/SQL alone. And it is!

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On identifiying "periods of activity"

I have a table that logs what items were bought at what time from a vending machine. Now, I want to find periods of activity on this machine.

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On a table's first five rows

Using rownum to select the first n rows does not always return the same records

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