August 2024
Intermediate to advanced
380 pages
10h 16m
Spanish
Content preview from Aprender SQL, 3ª Edición
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Capítulo 14. Vistas
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Las aplicaciones bien diseñadas suelen exponer una interfaz pública manteniendo en privado los detalles de implementación, lo que permite futuros cambios de diseño sin afectar a los usuarios finales. Al diseñar tu base de datos, puedes conseguir un resultado similar manteniendo tus tablas privadas y permitiendo que tus usuarios accedan a los datos sólo a través de un conjunto de vistas. Este capítulo pretende definir qué son las vistas, cómo se crean y cuándo y cómo puedes querer utilizarlas.
¿Qué son las opiniones?
Una vista es simplemente un mecanismo para consultar datos. A diferencia de las tablas, las vistas no implican almacenamiento de datos; no tendrás que preocuparte de que las vistas llenen tu espacio en disco. Creas una vista asignando un nombre a una sentencia select y almacenando después la consulta para que otros usuarios puedan utilizarla. Otros usuarios pueden utilizar tu vista para acceder a los datos como si consultaran directamente las tablas (de hecho, puede que ni siquiera sepan que están utilizando una vista).
Como ejemplo sencillo, digamos que quieres ocultar parcialmente la dirección de correo electrónico en la tabla customer. El departamento de marketing, por ejemplo, puede necesitar acceder a las direcciones de correo electrónico para anunciar promociones, pero por lo demás la política de privacidad de tu empresa ...
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