{"id":1780,"date":"2024-08-03T08:19:01","date_gmt":"2024-08-03T06:19:01","guid":{"rendered":"https:\/\/blog.sutilweb.eu\/?page_id=1780"},"modified":"2024-08-03T08:19:03","modified_gmt":"2024-08-03T06:19:03","slug":"12-concepto-de-crud","status":"publish","type":"page","link":"https:\/\/sutilweb.eu\/index.php\/lenguajes\/php\/poo-php\/12-concepto-de-crud\/","title":{"rendered":"12. Concepto de CRUD"},"content":{"rendered":"\n<p>El <strong>CRUD<\/strong> en las <strong>bases de datos<\/strong> significa:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>C: Create (crear)<\/li>\n\n\n\n<li>R: Read (leer)<\/li>\n\n\n\n<li>U: Update (actualizar)<\/li>\n\n\n\n<li>D: Delete (eliminar)<\/li>\n<\/ul>\n\n\n\n<!--more-->\n\n\n\n<p>Esto se traduce a las 4 operaciones m\u00e1s importantes que tiene el lenguaje SQL, que son:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Create: INSERT<\/li>\n\n\n\n<li>Read: SELECT<\/li>\n\n\n\n<li>Update: UPDATE<\/li>\n\n\n\n<li>Delete: DELETE<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Insertar un registro<\/h2>\n\n\n\n<p>Esta es la sintaxis utilizada para insertar un registro mediante la sentencia CREATE.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">INSERT INTO table(field1, field2, .... fieldn)\n   VALUES(value1, value2, ... valuen);<\/pre>\n\n\n\n<p>O bien<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">INSERT INTO table\n   SET field1 = 'value1', field2 = 'value2', ... fieldn = 'valuen';<\/pre>\n\n\n\n<p>Como vemos, hay dos maneras de insertar registros.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Insertar varios registros<\/h2>\n\n\n\n<p>Cuando tenemos varios registros podemos hacerlo de la siguiente forma.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">INSERT INTO table (field1, field2, ... fieldn) VALUES\n   (value1, value2, ... valuen),\n   (value1, value2, ... valuen),\n   (value1, value2, ... valuen);<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">Leer campos de una tabla<\/h2>\n\n\n\n<p>La sentencia que tendr\u00edamos que ejecutar es la siguiente.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT * FROM table;<\/pre>\n\n\n\n<p>Para leer algunos campos de una tabla se utiliza la siguiente sentencia.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT field1, field2, ... fieldn FROM table;<\/pre>\n\n\n\n<p>Para leer un registro en particular buscando el valor de un campo, la sintaxis ser\u00eda la siguiente.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT * FROM table WHERE field1 = 'value1';<\/pre>\n\n\n\n<p>Para leer un registro en particular buscando el valor de m\u00e1s de 2 campos con operadores l\u00f3gicos, la sintaxis ser\u00eda la siguiente.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT FROM table WHERE field1 = 'value1' AND field2 = 'value2';\nSELECT FROM table WHERE field1 = 'value1' OR field2 = 'value2';<\/pre>\n\n\n\n<p>Para leer un registro en particular buscando el valor similar de un campo utilizamos la siguiente sintaxis.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT * FROM table WHERE field1 LIKE '%valor1';\nSELECT * FROM table WHERE field1 LIKE 'valor1%';\nSELECT * FROM table WHERE field1 LIKE '%valor1%';<\/pre>\n\n\n\n<p>Saber cuantos registros tiene nuestra tabla se utiliza la siguiente sintaxis.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT COUNT(*) FROM table;<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">Actualizar campos de una tabla<\/h2>\n\n\n\n<p>Para actualizar registros de una tabla se utiliza la siguiente sintaxis.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">UPDATE table\n   SET field1 = 'value1', field2 = 'value2', ... fieln = 'valuen'\n   WHERE field = value;<\/pre>\n\n\n\n<p>Siempre tiene que llevar una cla\u00fasula WHERE para que no actualice todos los registros con el mismo valor.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Eliminar registros<\/h2>\n\n\n\n<p>Para eliminar registros utilizamos la siguiente sintaxis.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">DELETE FROM table WHERE field = value;<\/pre>\n\n\n\n<p>Como en UPDATE, es necesario incluir la cla\u00fasula WHERE para no eliminar todos los registros de una tabla.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>El CRUD en las bases de datos 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