{"id":245,"date":"2018-12-13T07:22:09","date_gmt":"2018-12-13T07:22:09","guid":{"rendered":"https:\/\/barkhane.com\/sql\/2018\/12\/13\/sql-join\/"},"modified":"2024-03-03T17:55:46","modified_gmt":"2024-03-03T17:55:46","slug":"sql-join","status":"publish","type":"post","link":"https:\/\/barkhane.com\/sql\/sql-join\/","title":{"rendered":"SQL JOIN"},"content":{"rendered":"

A SQL JOIN clause is used to combine rows from two or more tables<\/a>, based on a related column between them.<\/p>\n

Let\\’s look at a selection from the \\”Orders\\” table:<\/p>\n

\n\n\n\n\n\n\n
OrderID<\/th>\nCustomerID<\/th>\nOrderDate<\/th>\n<\/tr>\n
10308<\/td>\n2<\/td>\n1996-09-18<\/td>\n<\/tr>\n
10309<\/td>\n37<\/td>\n1996-09-19<\/td>\n<\/tr>\n
10310<\/td>\n77<\/td>\n1996-09-20<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Then, look at a selection from the \\”Customers\\” table:<\/p>\n

\n\n\n\n\n\n\n
CustomerID<\/th>\nCustomerName<\/th>\nContactName<\/th>\nCountry<\/th>\n<\/tr>\n
1<\/td>\nAlfreds Futterkiste<\/td>\nMaria Anders<\/td>\nGermany<\/td>\n<\/tr>\n
2<\/td>\nAna Trujillo Emparedados y helados<\/td>\nAna Trujillo<\/td>\nMexico<\/td>\n<\/tr>\n
3<\/td>\nAntonio Moreno Taquer\u00eda<\/td>\nAntonio Moreno<\/td>\nMexico<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Notice that the \\”CustomerID\\” column in the \\”Orders\\” table refers to the \\”CustomerID\\” in the \\”Customers\\” table. The relationship between the two tables above is the \\”CustomerID\\” column.<\/p>\n

Then, we can create the following SQL statement (that contains an INNER JOIN), that selects records that have matching values in both tables:<\/p>\n

\n

Example<\/h3>\n
SELECT\u00a0Orders.OrderID, Customers.CustomerName, Orders.OrderDate
\nFROM\u00a0Orders
\nINNER\u00a0JOIN\u00a0Customers\u00a0ON\u00a0Orders.CustomerID=Customers.CustomerID;<\/div>\n<\/div>\n

and it will produce something like this:<\/p>\n

\n

Different Types of SQL JOINs<\/h2>\n

Here are the different types of the JOINs in SQL:<\/p>\n

    \n
  • (INNER) JOIN<\/b>: Returns records that have matching values in both tables<\/li>\n
  • LEFT (OUTER) JOIN<\/b>: Return all records from the left table, and the matched records from the right table<\/li>\n
  • RIGHT (OUTER) JOIN<\/b>: Return all records from the right table, and the matched records from the left table<\/li>\n
  • FULL (OUTER) JOIN<\/b>: Return all records when there is a match in either left or right table<\/li>\n<\/ul>\n

    \"\"<\/p>\n","protected":false},"excerpt":{"rendered":"

    A SQL JOIN clause is used to combine rows from two or more tables, based on a related column between […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"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 center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[2],"tags":[],"class_list":["post-245","post","type-post","status-publish","format-standard","hentry","category-sql"],"_links":{"self":[{"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/posts\/245","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/comments?post=245"}],"version-history":[{"count":0,"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/posts\/245\/revisions"}],"wp:attachment":[{"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/media?parent=245"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/categories?post=245"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/barkhane.com\/sql\/wp-json\/wp\/v2\/tags?post=245"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}