August 2024
Intermediate to advanced
380 pages
10h 16m
Spanish
Content preview from Aprender SQL, 3ª Edición
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Capítulo 1. Un poco de historia
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Antes de arremangarnos y ponernos manos a la obra, sería útil repasar la historia de la tecnología de bases de datos para comprender mejor cómo evolucionaron las bases de datos relacionales y el lenguaje SQL. Por tanto, me gustaría empezar introduciendo algunos conceptos básicos de las bases de datos y repasando la historia del almacenamiento y la recuperación de datos informatizados.
Nota
Para aquellos lectores ansiosos por empezar a escribir consultas, no duden en pasar al Capítulo 3, pero les recomiendo que vuelvan más tarde a los dos primeros capítulos para comprender mejor la historia y la utilidad del lenguaje SQL.
Introducción a las bases de datos
Una base de datos no es más que un conjunto de información relacionada. Una guía telefónica, por ejemplo, es una base de datos con los nombres, números de teléfono y direcciones de todas las personas que viven en una región determinada. Aunque una guía telefónica es sin duda una base de datos omnipresente y de uso frecuente, adolece de lo siguiente:
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Encontrar el número de teléfono de una persona puede llevar mucho tiempo, sobre todo si la guía telefónica contiene un gran número de entradas.
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Una guía telefónica sólo está indexada por apellidos y nombres, por lo que encontrar los nombres de las personas que viven en una dirección concreta, aunque es posible en teoría, no es ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.