{"id":1157,"date":"2024-07-31T11:33:54","date_gmt":"2024-07-31T09:33:54","guid":{"rendered":"https:\/\/blog.sutilweb.eu\/?page_id=1157"},"modified":"2024-07-31T11:33:54","modified_gmt":"2024-07-31T09:33:54","slug":"36-transacciones","status":"publish","type":"page","link":"https:\/\/sutilweb.eu\/index.php\/databases\/sql\/36-transacciones\/","title":{"rendered":"36. Transacciones"},"content":{"rendered":"\n<p>Una <strong>transacci\u00f3n<\/strong> es un <strong>conjunto de instrucciones SQL<\/strong> que podemos ejecutar una tras de otra, y si en alg\u00fan momento falla algo en alguna de esas transacciones, en alguna de esas sentencias, y por alguna raz\u00f3n, se hace un <strong>rollback<\/strong> regresando a la versi\u00f3n de como estaba la <strong>base de datos<\/strong> antes de comenzar la <strong>transacci\u00f3n.<\/strong><\/p>\n\n\n\n<!--more-->\n\n\n\n<p>Esto es muy importante sobre todo en procesos donde necesitamos modificar la data de diferentes <strong>tablas.<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Sintaxis<\/h2>\n\n\n\n<p>Una transacci\u00f3n comienza con el uso de la palabra <strong><em>START,<\/em><\/strong> veamos un ejm.<\/p>\n\n\n\n<p><strong>Ejm<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">START TRANSACTION;\n\/* CODIGO QUE QUEREMOS EJECUTAR*\/\n\nROLLBACK; -- Si da error utilizamos este comando y vuelve a la versi\u00f3n que ten\u00edamos\nCOMMIT; -- Si no da error utilizamos este comando<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">Cla\u00fasula <em>LIMIT<\/em><\/h2>\n\n\n\n<p>Podemos limitar el n\u00famero de datos a mostrar en un <strong><em>SELECT.<\/em><\/strong> Veamos un ejm.<\/p>\n\n\n\n<p><strong>Ejm<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">-- Muestra los registros de 10 en 10\nSELECT * FROM bandas LIMIT 10;\n\n-- Muestra 20 registros comenzando por el registro 10\nSELECT * FROM bandas LIMIT 10, 20; (se coloca en el registro 10 y muestra 20 registros)<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Una transacci\u00f3n es un conjunto de instrucciones SQL que podemos ejecutar una tras de otra, y si en alg\u00fan momento [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1076,"menu_order":35,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_uag_custom_page_level_css":"","site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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