{"id":178993,"date":"2024-04-23T16:04:44","date_gmt":"2024-04-23T15:04:44","guid":{"rendered":"https:\/\/datascientest.com\/en\/?p=178993"},"modified":"2024-02-17T17:05:58","modified_gmt":"2024-02-17T16:05:58","slug":"primary-key-definition-advantages-and-special-features","status":"publish","type":"post","link":"https:\/\/datascientest.com\/en\/primary-key-definition-advantages-and-special-features","title":{"rendered":"Primary key: Definition, advantages and special features"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"178993\" class=\"elementor elementor-178993\" data-elementor-post-type=\"post\">\n\t\t\t\t\t\t\t<div class=\"elementor-element elementor-element-fc41f84 e-flex e-con-boxed e-con\" data-id=\"fc41f84\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a2fbd25 elementor-widget elementor-widget-heading\" data-id=\"a2fbd25\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style>\/*! elementor - v3.15.0 - 02-08-2023 *\/\n.elementor-heading-title{padding:0;margin:0;line-height:1}.elementor-widget-heading .elementor-heading-title[class*=elementor-size-]>a{color:inherit;font-size:inherit;line-height:inherit}.elementor-widget-heading .elementor-heading-title.elementor-size-small{font-size:15px}.elementor-widget-heading .elementor-heading-title.elementor-size-medium{font-size:19px}.elementor-widget-heading .elementor-heading-title.elementor-size-large{font-size:29px}.elementor-widget-heading .elementor-heading-title.elementor-size-xl{font-size:39px}.elementor-widget-heading .elementor-heading-title.elementor-size-xxl{font-size:59px}<\/style><h2 class=\"elementor-heading-title elementor-size-default\">Relational databases contain thousands and thousands of rows. To simplify processing, it is vital to identify the different records in a table clearly and efficiently. This is where primary keys come in. <\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-ab17409 e-flex e-con-boxed e-con\" data-id=\"ab17409\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-f210b08 elementor-widget elementor-widget-heading\" data-id=\"f210b08\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Primary keys, unique fields in your data table<\/h3>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-828db6b elementor-widget elementor-widget-text-editor\" data-id=\"828db6b\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style>\/*! elementor - v3.15.0 - 02-08-2023 *\/\n.elementor-widget-text-editor.elementor-drop-cap-view-stacked .elementor-drop-cap{background-color:#69727d;color:#fff}.elementor-widget-text-editor.elementor-drop-cap-view-framed .elementor-drop-cap{color:#69727d;border:3px solid;background-color:transparent}.elementor-widget-text-editor:not(.elementor-drop-cap-view-default) .elementor-drop-cap{margin-top:8px}.elementor-widget-text-editor:not(.elementor-drop-cap-view-default) .elementor-drop-cap-letter{width:1em;height:1em}.elementor-widget-text-editor .elementor-drop-cap{float:left;text-align:center;line-height:1;font-size:50px}.elementor-widget-text-editor .elementor-drop-cap-letter{display:inline-block}<\/style>\t\t\t\t<p>The <strong>primary key<\/strong> refers to one (or more) attribute(s) which allows records to be fully differentiated. In practical terms, it is a single field for all the records in a table.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-6619da2 elementor-widget elementor-widget-heading\" data-id=\"6619da2\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">The advantages of a primary key<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-41df534 elementor-widget elementor-widget-text-editor\" data-id=\"41df534\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>The purpose of <strong>primary keys<\/strong> is to structure the database so that it is easier to identify the rows in the table. In doing so, primary keys make it possible to:<\/p><ul><li><a href=\"https:\/\/datascientest.com\/en\/data-quality-10-mistakes-not-to-make\"><strong>Guarantee data integrity and accuracy:<\/strong> <\/a>each row is only recorded once and no important information is lost.<\/li><li><strong>Simplify the update process:<\/strong> simply select the different primary keys to modify or delete rows.<\/li><li>Quicker access to data: if you know the table&#8217;s primary key, you can access the data you need more easily.<\/li><\/ul>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-355dfc2 elementor-align-center button-principale elementor-widget elementor-widget-button\" data-id=\"355dfc2\" data-element_type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<div class=\"elementor-button-wrapper\">\n\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-sm elementor-animation-grow\" href=\"https:\/\/datascientest.com\/en\/data-courses\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t<span class=\"elementor-button-text\">Learn how to use primary keys<\/span>\n\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cff8897 elementor-widget elementor-widget-heading\" data-id=\"cff8897\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">Example of a primary key<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-51e2af5 elementor-widget elementor-widget-text-editor\" data-id=\"51e2af5\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>To help you better <strong>understand primary keys,<\/strong> here is an example:<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-49be09a elementor-widget elementor-widget-html\" data-id=\"49be09a\" data-element_type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style type=\"text\/css\">\r\n.tg  {border-collapse:collapse;border-spacing:0;}\r\n.tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px;\r\n  overflow:hidden;padding:10px 5px;word-break:normal;}\r\n.tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px;\r\n  font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;}\r\n.tg .tg-z2m2{background-color:#6434fc;color:#efefef;font-family:\"Trebuchet MS\", Helvetica, sans-serif !important;font-size:20px;\r\n  font-weight:bold;text-align:center;vertical-align:top}\r\n.tg .tg-4lje{font-family:\"Trebuchet MS\", Helvetica, sans-serif !important;text-align:center;vertical-align:top}\r\n<\/style>\r\n<table class=\"tg\" style=\"undefined;table-layout: fixed; width: 250px\">\r\n<colgroup>\r\n<col style=\"width: 100px\">\r\n<col style=\"width: 100px\">\r\n<col style=\"width: 50px\">\r\n<\/colgroup>\r\n<thead>\r\n  <tr>\r\n    <th class=\"tg-z2m2\">Name<\/th>\r\n    <th class=\"tg-z2m2\">First Name<\/th>\r\n    <th class=\"tg-z2m2\">Age<\/th>\r\n  <\/tr>\r\n<\/thead>\r\n<tbody>\r\n  <tr>\r\n    <td class=\"tg-4lje\">Dupont<\/td>\r\n    <td class=\"tg-4lje\">Jeanne<\/td>\r\n    <td class=\"tg-4lje\">25<\/td>\r\n  <\/tr>\r\n  <tr>\r\n    <td class=\"tg-4lje\">Leroy<\/td>\r\n    <td class=\"tg-4lje\">Marie<\/td>\r\n    <td class=\"tg-4lje\">21<\/td>\r\n  <\/tr>\r\n  <tr>\r\n    <td class=\"tg-4lje\">Dupont <\/td>\r\n    <td class=\"tg-4lje\">Pierre<\/td>\r\n    <td class=\"tg-4lje\">21<\/td>\r\n  <\/tr>\r\n<\/tbody>\r\n<\/table>\r\n\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a6df5d7 elementor-widget elementor-widget-text-editor\" data-id=\"a6df5d7\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>In this example, only the &#8220;First name&#8221; attribute is used to differentiate the rows in the table. And for good reason, in the name, &#8220;Smith&#8221; is found 2 times. The same applies to age 21. The first name attribute is therefore a primary key.<\/p><p>However, this is no longer the case with the following table:<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-676ccd1 elementor-widget elementor-widget-html\" data-id=\"676ccd1\" data-element_type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style type=\"text\/css\">\r\n.tg  {border-collapse:collapse;border-spacing:0;}\r\n.tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px;\r\n  overflow:hidden;padding:10px 5px;word-break:normal;}\r\n.tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px;\r\n  font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;}\r\n.tg .tg-z2m2{background-color:#6434fc;color:#efefef;font-family:\"Trebuchet MS\", Helvetica, sans-serif !important;font-size:20px;\r\n  font-weight:bold;text-align:center;vertical-align:top}\r\n.tg .tg-4lje{font-family:\"Trebuchet MS\", Helvetica, sans-serif !important;text-align:center;vertical-align:top}\r\n<\/style>\r\n<table class=\"tg\" style=\"undefined;table-layout: fixed; width: 250px\">\r\n<colgroup>\r\n<col style=\"width: 100px\">\r\n<col style=\"width: 100px\">\r\n<col style=\"width: 50px\">\r\n<\/colgroup>\r\n<thead>\r\n  <tr>\r\n    <th class=\"tg-z2m2\">Name<\/th>\r\n    <th class=\"tg-z2m2\">First Name<\/th>\r\n    <th class=\"tg-z2m2\">Age<\/th>\r\n  <\/tr>\r\n<\/thead>\r\n<tbody>\r\n  <tr>\r\n    <td class=\"tg-4lje\">Dupont<\/td>\r\n    <td class=\"tg-4lje\">Jeanne<\/td>\r\n    <td class=\"tg-4lje\">25<\/td>\r\n  <\/tr>\r\n  <tr>\r\n    <td class=\"tg-4lje\">Leroy<\/td>\r\n    <td class=\"tg-4lje\">Jeanne<\/td>\r\n    <td class=\"tg-4lje\">21<\/td>\r\n  <\/tr>\r\n  <tr>\r\n    <td class=\"tg-4lje\">Dupont <\/td>\r\n    <td class=\"tg-4lje\">Pierre<\/td>\r\n    <td class=\"tg-4lje\">21<\/td>\r\n  <\/tr>\r\n<\/tbody>\r\n<\/table>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-10031ba elementor-widget elementor-widget-text-editor\" data-id=\"10031ba\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>In this case, no single attribute can be used to differentiate between records. So you need to select several attributes, such as surname + first name. By combining the two, you can see that there is never the same line twice. Here, the last name + first name attributes constitute a primary key.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f6004b0 elementor-widget elementor-widget-text-editor\" data-id=\"f6004b0\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p><strong>Good to know:<\/strong><a href=\"https:\/\/datascientest.com\/en\/datasets-top-5-places-to-find-quality-datasets\"> databases<\/a> often contain an ID attribute which serves as the primary key. This involves assigning a distinct number to each row (1,2,3,4&#8230;). This primary key is created automatically at the very beginning of the table (column A) in order to differentiate each record.<\/p><p>This is why the term primary key is very often confused with identifier. Although the two are often identical, this is not automatic.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-26e0fc9 e-flex e-con-boxed e-con\" data-id=\"26e0fc9\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-00bf2b0 elementor-widget elementor-widget-heading\" data-id=\"00bf2b0\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The different types of primary key<\/h3>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-6f8ae4f elementor-widget elementor-widget-text-editor\" data-id=\"6f8ae4f\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>There are different types of <strong>primary keys<\/strong>. The most common are :<\/p><ul><li><strong>Natural keys:<\/strong> these are attributes that contain significant information (without which it is impossible to make a mistake). This is the case, for example, with a social security number.<\/li><li><strong>Substitution keys:<\/strong> these are artificial keys, such as an automatically generated number.<\/li><li><strong>Composite keys:<\/strong> this is a combination of several attributes, such as the first and last names of customers.<\/li><\/ul>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-2ab7703 e-flex e-con-boxed e-con\" data-id=\"2ab7703\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-52700c6 elementor-widget elementor-widget-heading\" data-id=\"52700c6\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Primary and foreign keys<\/h3>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-54b61cc elementor-widget elementor-widget-text-editor\" data-id=\"54b61cc\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>The <strong>ultimate purpose of the primary key<\/strong> is to link related records in other tables. For example, the customer ID can be used in a table grouping all the company&#8217;s customers and another table grouping customers by salesperson.<\/p><p>This is where <strong>foreign keys<\/strong> come into play. These are one or more attributes which are the primary key in an A table and which are used to characterise the elements in a B table. In this case, it is generally the ID (of a customer, a product, an employee, etc.) that is used in several different tables.<\/p><p>To find out more about <a href=\"https:\/\/datascientest.com\/en\/how-to-choose-a-data-governance-course\">data management<\/a>, sign up for one of our training courses.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-595d38b elementor-widget__width-initial elementor-widget elementor-widget-video\" data-id=\"595d38b\" data-element_type=\"widget\" data-settings=\"{&quot;youtube_url&quot;:&quot;https:\\\/\\\/youtu.be\\\/9UIHp6DCjbU&quot;,&quot;video_type&quot;:&quot;youtube&quot;,&quot;controls&quot;:&quot;yes&quot;}\" data-widget_type=\"video.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style>\/*! elementor - v3.15.0 - 02-08-2023 *\/\n.elementor-widget-video .elementor-widget-container{overflow:hidden;transform:translateZ(0)}.elementor-widget-video .elementor-wrapper{aspect-ratio:var(--video-aspect-ratio)}.elementor-widget-video .elementor-wrapper iframe,.elementor-widget-video .elementor-wrapper video{height:100%;width:100%;display:flex;border:none;background-color:#000}@supports not (aspect-ratio:1\/1){.elementor-widget-video .elementor-wrapper{position:relative;overflow:hidden;height:0;padding-bottom:calc(100% \/ var(--video-aspect-ratio))}.elementor-widget-video .elementor-wrapper iframe,.elementor-widget-video .elementor-wrapper video{position:absolute;top:0;right:0;bottom:0;left:0}}.elementor-widget-video .elementor-open-inline .elementor-custom-embed-image-overlay{position:absolute;top:0;right:0;bottom:0;left:0;background-size:cover;background-position:50%}.elementor-widget-video .elementor-custom-embed-image-overlay{cursor:pointer;text-align:center}.elementor-widget-video .elementor-custom-embed-image-overlay:hover .elementor-custom-embed-play i{opacity:1}.elementor-widget-video .elementor-custom-embed-image-overlay img{display:block;width:100%;aspect-ratio:var(--video-aspect-ratio);-o-object-fit:cover;object-fit:cover;-o-object-position:center center;object-position:center center}@supports not (aspect-ratio:1\/1){.elementor-widget-video .elementor-custom-embed-image-overlay{position:relative;overflow:hidden;height:0;padding-bottom:calc(100% \/ var(--video-aspect-ratio))}.elementor-widget-video .elementor-custom-embed-image-overlay img{position:absolute;top:0;right:0;bottom:0;left:0}}.elementor-widget-video .e-hosted-video .elementor-video{-o-object-fit:cover;object-fit:cover}.e-con-inner>.elementor-widget-video,.e-con>.elementor-widget-video{width:var(--container-widget-width);--flex-grow:var(--container-widget-flex-grow)}<\/style>\t\t<div class=\"elementor-wrapper elementor-open-inline\">\n\t\t\t<div class=\"elementor-video\"><\/div>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-698ec0c elementor-align-center button-principale elementor-widget elementor-widget-button\" data-id=\"698ec0c\" data-element_type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<div class=\"elementor-button-wrapper\">\n\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-sm elementor-animation-grow\" href=\"https:\/\/datascientest.com\/en\/data-courses\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t<span class=\"elementor-button-text\">Join the DataScientest training courses<\/span>\n\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-461d7d8 e-flex e-con-boxed e-con\" data-id=\"461d7d8\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-081f85d elementor-widget elementor-widget-heading\" data-id=\"081f85d\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Key facts:<\/h3>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8ecd223 elementor-widget elementor-widget-text-editor\" data-id=\"8ecd223\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<ul><li style=\"font-weight: 400;\" aria-level=\"1\">Primary keys are unique fields used to differentiate rows in a database.<\/li><li style=\"font-weight: 400;\" aria-level=\"1\">Most of the time, primary keys are IDs (or identifiers). But this is not always the case.<\/li><li style=\"font-weight: 400;\" aria-level=\"1\">Foreign keys are used to link data between different tables.<\/li><\/ul>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-e463940 e-flex e-con-boxed e-con\" data-id=\"e463940\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-7fcb43e elementor-widget elementor-widget-html\" data-id=\"7fcb43e\" data-element_type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [{\n    \"@type\": \"Question\",\n    \"name\": \"Primary keys, unique fields in your data table\",\n    \"acceptedAnswer\": {\n      \"@type\": \"Answer\",\n      \"text\": \"The primary key refers to one (or more) attribute(s) which allow(s) the records to be completely differentiated. 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Primary keys, unique fields in your data table The primary key refers to one (or more) attribute(s) which allows records to be fully [&hellip;]<\/p>\n","protected":false},"author":67,"featured_media":178997,"comment_status":"open","ping_status":"open","sticky":false,"template":"elementor_theme","format":"standard","meta":{"content-type":"","inline_featured_image":false},"categories":[2425],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.7 (Yoast SEO v21.7) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Primary key: Definition, advantages and special features<\/title>\n<meta name=\"description\" content=\"The concept of the Primary Key is important, especially when you waznt to use Primary Keys in your projects, you have to...\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/datascientest.com\/en\/primary-key-definition-advantages-and-special-features\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Primary key: Definition, advantages and special features\" \/>\n<meta property=\"og:description\" content=\"Relational databases contain thousands and thousands of rows. 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