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June 3, 2023
Oracle World :: Developer's Cheat Sheet

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SQL Basic

SQL Basic

Permissions

October 28, 2018April 17, 2020 - by OracleWorld

There is a need for an access control mechanism implemented in a multi-user environment. You have to be able to control who can access what. Thus Oracle implemented privileges to …

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SQL Basic

DDL Statements

October 5, 2018November 10, 2020 - by OracleWorld

DDL (stands for Data Definition Language) statements are used for objects creation. I might write a book on this topic because there are many different objects in a database and …

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SQL Basic

DML statements

October 4, 2018February 5, 2019 - by OracleWorld

DML (stands for Data Manipulation Language) statements are used to manipulate (add, delete, modify) data. They support transactions. What is a transaction? It means that no matter what changes you …

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SQL Basic

Set Operators & Compound Queries

October 4, 2018November 10, 2020 - by OracleWorld

Set operators are used to combine multiple queries together. We call such queries “compound queries”.  All set operators have the same precedence unless parentheses are usedYou can only combine queries …

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SQL Basic

Subqueries

October 4, 2018February 5, 2019 - by OracleWorld

Subqueries come in handy when it comes to a complex logic. There are many cases where it is easier to tackle the problem using subqueries. Let me start with an …

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SQL Basic

Displaying Data From Multiple Tables

October 4, 2018November 10, 2020 - by OracleWorld

The solution for the need of data extraction from multiple tables, whether it is for a purpose of comparison or to display them together, lies in JOINs. There are three …

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SQL Basic

Data Aggregation Using GROUP BY

October 4, 2018November 10, 2020 - by OracleWorld

Anytime you need to aggregate some data you have to define two things: what are the dimensions what are the facts First of all, what is a dimension and what …

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SQL Basic

Conditional Expressions

October 4, 2018November 10, 2020 - by OracleWorld

In any programming or scripting language, we have to implement a decision logic. SQL is no different and Oracle comes with two easy directives how to handle it; they are …

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SQL Basic

Single-Row Functions

October 3, 2018November 10, 2020 - by OracleWorld

These functions return a value for each record for a queried table or a view. There are 7 main categories listed below. Numeric Character returning number returning character Date / Date …

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SQL Basic

Restricting and Sorting Data

October 2, 2018April 17, 2020 - by OracleWorld

In order to customize your data selection, you might be needing to restrict / filter out some data and sort / order them. To do so, you need to use …

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SQL Basic

SELECT statement (decomposed)

October 2, 2018December 15, 2020 - by OracleWorld

The most commonly used and basic type of SQL (stands for Structured Query Language) is a SELECT statement. SELECT With the SELECT statement, we can retrieve data from a table. …

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SQL Basic

NULL

October 2, 2018December 15, 2020 - by OracleWorld

What is NULL? NULL values have a special function. They represent nothing 🙂 Anytime you see NULL in a table that means there is nothing. Blank space, zero and NULL …

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SQL Basic

Database Objects

October 2, 2018December 15, 2020 - by OracleWorld

Database objects relate to schema and non-schema objects. Schema objects – a collection of logical structures of data related to a  schema Clusters A cluster is an object that contains data …

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SQL Basic

User, Schema and Role

October 2, 2018December 15, 2020 - by OracleWorld

In order to maintain security in a multi-user environment, you have to define different access types for different users. Many people wonder what is the difference between a user and …

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SQL Basic

Database Design: ERD, NFs

October 1, 2018December 15, 2020 - by OracleWorld

All projects start with a design. Polished database design is necessary to have a successful business. Even if your queries are optimized and tuned to perfection you will not be able to …

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SQL Basic

DBMS and Other Relational Models

October 1, 2018November 10, 2020 - by OracleWorld

DataBase Management System (DBMS) controls the storage, management/organization, and retrieval of data. DBMS consists of three major parts: Kernel code Data dictionary (metadata) Query language The most widely known and used …

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About Me

Hello, my name is Petr Hybler and I am an Oracle enthusiast and a professional Data whisperer. My journey started even before …

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