Base de données orientée texte

A flat-file database is a database stored in a file called a flat file. Records follow a uniform format, and there are no structures for indexing or recognizing relationships between records. The file is simple. A flat file can be a plain text file (e.g. csv, or tsv), or a . Relationships can be inferred from the data in the database, but the database format itself does not make those relationships explicit. The term has generally implied a small database, but very large databases can also be flat. Plain text files usually contain one record per line. There are different conventions for depicting data. In comma-separated values and delimiter-separated values files, fields can be separated by delimiters such as comma or tab characters. In other cases, each field may have a fixed length; short values may be padded with space characters. Extra formatting may be needed to avoid delimiter collision. Using delimiters incurs some overhead in locating them every time they are processed (unlike fixed-width formatting), which may have performance implications. However, use of character delimiters (especially commas) is also a crude form of data compression which may assist overall performance by reducing data volumes — especially for data transmission purposes. Use of character delimiters which include a length component (Declarative notation) is comparatively rare but vastly reduces the overhead associated with locating the extent of each field. Examples of flat files include /etc/passwd and /etc/group on Unix-like operating systems. Another example of a flat file is a name-and-address list with the fields Name, Address, and Phone Number. A list of names, addresses, and phone numbers written by hand on a sheet of paper is a flat-file database. This can also be done with any typewriter or word processor. A spreadsheet or text editor program may be used to implement a flat-file database, which may then be printed or used online for improved search capabilities.

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Concepts associés (11)

Cours associés (9)

Séances de cours associées (61)

ENG-209: Data science for engineers with Python

Ce cours est divisé en deux partie. La première partie présente le langage Python et les différences notables entre Python et C++ (utilisé dans le cours précédent ICC). La seconde partie est une intro

COM-490: Large-scale data science for real-world data

This hands-on course teaches the tools & methods used by data scientists, from researching solutions to scaling up prototypes to Spark clusters. It exposes the students to the entire data science pipe

ENG-270: Computational methods and tools

This course prepares students to use modern computational methods and tools for solving problems in engineering and science.

Delimiter-separated values

Formats that use delimiter-separated values (also DSV) store two-dimensional arrays of data by separating the values in each row with specific delimiter characters. Most database and spreadsheet programs are able to read or save data in a delimited format. Due to their wide support, DSV files can be used in data exchange among many applications. A delimited text file is a used to store data, in which each line represents a single book, company, or other thing, and each line has fields separated by the delimiter.

Table (base de données)

thumb|Exemple de table de base de données Dans les bases de données relationnelles, une table est un ensemble de données organisées sous forme d'un tableau où les colonnes correspondent à des catégories d'information (une colonne peut stocker des numéros de téléphone, une autre des noms...) et les lignes à des enregistrements, également appelés entrées. Chaque table est l'implémentation physique d'une relation entre les différentes colonnes. Chaque correspondance est définie par une ligne de la table.

Tabulation-separated values

Tab-separated values (TSV) is a simple, for storing tabular data. Records are separated by newlines, and values within a record are separated by tab characters. The TSV format is thus a delimiter-separated values format, similar to comma-separated values. TSV is a simple file format that is widely supported, so it is often used in data exchange to move tabular data between different computer programs that support the format. For example, a TSV file might be used to transfer information from a database to a spreadsheet.

Analyse et prévision des données Excel

Couvre les bases de l'analyse des données Excel et des techniques de prévision.

Chimie quantique : Opérateurs de spin CH-244: Quantum chemistry

Explore les opérateurs de spin en chimie quantique, en se concentrant sur leurs propriétés et les règles de commutation avec les opérateurs d'impulsion angulaire orbitale.

Gestion des inscriptions

Explique le processus d'inscription et de désinscription des apprenants dans un cours.