September 2024
Intermediate to advanced
514 pages
13h 29m
Spanish
Content preview from MongoDB: La Guía Definitiva, 3ª EdiciónBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
Capítulo 4. Consulta de
Este trabajo se ha traducido utilizando IA. Agradecemos tus opiniones y comentarios: translation-feedback@oreilly.com
Este capítulo de trata en detalle las consultas. Las principales áreas tratadas son las siguientes:
Puedes consultar rangos, inclusión de conjuntos, desigualdades y mucho más utilizando las condicionales de
$.Las consultas devuelven un cursor de base de datos, que devuelve perezosamente lotes de documentos a medida que los necesitas.
Hay muchas metaoperaciones que puedes realizar en un cursor, como omitir un determinado número de resultados, limitar el número de resultados devueltos y ordenar los resultados.
Introducción al hallazgo
El método find se utiliza para realizar consultas en MongoDB. La consulta devuelve un subconjunto de documentos de una colección, desde ningún documento hasta toda la colección. Los documentos que se devuelven vienen determinados por el primer argumento de find, que es un documento que especifica los criterios de consulta.
Un documento de consulta vacío (es decir, {}) coincide con todo lo que hay en la colección. Si a find no se le asigna un documento de consulta, por defecto será {}. Por ejemplo, lo siguiente:
>db.c.find()
coincide con todos los documentos de la colección c (y devuelve estos documentos por lotes).
Cuando empezamos a añadir pares clave/valor al documento de consulta, empezamos a restringir nuestra búsqueda. Esto funciona de forma sencilla para la mayoría de los tipos: los números coinciden con los números, ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.