{"id":3459,"date":"2017-08-15T18:23:42","date_gmt":"2017-08-15T15:23:42","guid":{"rendered":"http:\/\/kamil-abzalov.com\/tutorials\/mysql-links-between-tables-foreign-keys\/"},"modified":"2020-04-08T23:55:11","modified_gmt":"2020-04-08T20:55:11","slug":"mysql-links-between-tables-foreign-keys","status":"publish","type":"post","link":"https:\/\/kamil-abzalov.com\/en\/tutorials\/mysql\/mysql-links-between-tables-foreign-keys\/","title":{"rendered":"MySQL. Links between tables. Foreign keys"},"content":{"rendered":"<p>[et_pb_section fb_built=&#8221;1&#8243; fullwidth=&#8221;on&#8221; _builder_version=&#8221;3.22&#8243;][et_pb_fullwidth_header title=&#8221;MySQL. Links between tables. Foreign keys&#8221; content_max_width=&#8221;none&#8221; _builder_version=&#8221;3.16&#8243; button_one_letter_spacing_hover=&#8221;0&#8243; button_two_letter_spacing_hover=&#8221;0&#8243; button_one_text_size__hover_enabled=&#8221;off&#8221; button_two_text_size__hover_enabled=&#8221;off&#8221; button_one_text_color__hover_enabled=&#8221;off&#8221; button_two_text_color__hover_enabled=&#8221;off&#8221; button_one_border_width__hover_enabled=&#8221;off&#8221; button_two_border_width__hover_enabled=&#8221;off&#8221; button_one_border_color__hover_enabled=&#8221;off&#8221; button_two_border_color__hover_enabled=&#8221;off&#8221; button_one_border_radius__hover_enabled=&#8221;off&#8221; button_two_border_radius__hover_enabled=&#8221;off&#8221; button_one_letter_spacing__hover_enabled=&#8221;on&#8221; button_one_letter_spacing__hover=&#8221;0&#8243; button_two_letter_spacing__hover_enabled=&#8221;on&#8221; button_two_letter_spacing__hover=&#8221;0&#8243; button_one_bg_color__hover_enabled=&#8221;off&#8221; button_two_bg_color__hover_enabled=&#8221;off&#8221;][\/et_pb_fullwidth_header][\/et_pb_section][et_pb_section fb_built=&#8221;1&#8243; admin_label=&#8221;section&#8221; _builder_version=&#8221;3.22&#8243;][et_pb_row admin_label=&#8221;row&#8221; _builder_version=&#8221;3.25&#8243; background_size=&#8221;initial&#8221; background_position=&#8221;top_left&#8221; background_repeat=&#8221;repeat&#8221; custom_padding=&#8221;0px|||&#8221;][et_pb_column type=&#8221;4_4&#8243; _builder_version=&#8221;3.25&#8243; custom_padding=&#8221;|||&#8221; custom_padding__hover=&#8221;|||&#8221;][et_pb_dcsbcm_divi_breadcrumbs_module homebreadcrumbtext=&#8221;Home&#8221; hide_currentbreadcrumb=&#8221;off&#8221; _builder_version=&#8221;4.4.2&#8243; custom_padding=&#8221;0px|||&#8221; hover_enabled=&#8221;0&#8243; fontsbreadcrumbs_font_size_tablet=&#8221;51&#8243; fontsbreadcrumbs_line_height_tablet=&#8221;2&#8243; fontsseperator_font_size_tablet=&#8221;51&#8243; fontsseperator_line_height_tablet=&#8221;2&#8243; fontsbreadcrumblinks_font_size_tablet=&#8221;51&#8243; fontsbreadcrumblinks_line_height_tablet=&#8221;2&#8243;][\/et_pb_dcsbcm_divi_breadcrumbs_module][et_pb_text _builder_version=&#8221;3.27.4&#8243; background_size=&#8221;initial&#8221; background_position=&#8221;top_left&#8221; background_repeat=&#8221;repeat&#8221; use_border_color=&#8221;off&#8221; border_color=&#8221;#ffffff&#8221; border_style=&#8221;solid&#8221;]In this lesson we will consider links between tables, types these links and foreign keys. Links between tables need for quickly getting data. Let&#8217;s imagine, you are in the shop and would like to buy fruits. If all fruits will be in one box you will need more time to search 10 apples, for example. If apples are in one box, oranges are in second box (and so on), it is more comfortable and quick to put fruits to your basket. The same way uses in tables.<!--more--><br \/>\n[\/et_pb_text][et_pb_video src=&#8221;https:\/\/www.youtube.com\/watch?v=8XubzWm3ANY&#8221; _builder_version=&#8221;3.0.47&#8243;][\/et_pb_video][et_pb_text _builder_version=&#8221;3.27.4&#8243; background_size=&#8221;initial&#8221; background_position=&#8221;top_left&#8221; background_repeat=&#8221;repeat&#8221; use_border_color=&#8221;off&#8221; border_color=&#8221;#ffffff&#8221; border_style=&#8221;solid&#8221;]Remember last lesson &#8211; we created table, which stored teams, players and countries. It wasn&#8217;t right way to organize data store. Getting data form such table is not comfortable. 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Links between tables need for quickly getting data. Let&#8217;s imagine, you are in the shop and would like to buy fruits. If all fruits will be in one box you will need more time to search 10 apples, for example. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"\u0412 \u044d\u0442\u043e\u043c \u0432\u0438\u0434\u0435\u043e\u0443\u0440\u043e\u043a\u0435 \u043c\u044b \u0440\u0430\u0441\u0441\u043c\u043e\u0442\u0440\u0438\u043c \u0441\u0432\u044f\u0437\u0438 \u043c\u0435\u0436\u0434\u0443 \u0442\u0430\u0431\u043b\u0438\u0446\u0430\u043c\u0438, \u0432\u0438\u0434\u044b \u0441\u0432\u044f\u0437\u0435\u0439 \u043c\u0435\u0436\u0434\u0443 \u0442\u0430\u0431\u043b\u0438\u0446\u0430\u043c\u0438 \u0438 \u0432\u043d\u0435\u0448\u043d\u0438\u0435 \u043a\u043b\u044e\u0447\u0438. \u0421\u0432\u044f\u0437\u0438 \u043c\u0435\u0436\u0434\u0443 \u0442\u0430\u0431\u043b\u0438\u0446\u0430\u043c\u0438 \u043d\u0435\u043e\u0431\u0445\u043e\u0434\u0438\u043c\u044b \u0434\u043b\u044f \u0431\u043e\u043b\u0435\u0435 \u0431\u044b\u0441\u0442\u0440\u043e\u0433\u043e \u0434\u043e\u0441\u0442\u0443\u043f\u0430 \u043a \u0434\u0430\u043d\u043d\u044b\u043c. \u0414\u0430\u0432\u0430\u0439\u0442\u0435 \u043f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u0438\u043c, \u0447\u0442\u043e \u0432\u044b \u043f\u0440\u0438\u0448\u043b\u0438 \u0432 \u043c\u0430\u0433\u0430\u0437\u0438\u043d \u0438 \u0445\u043e\u0442\u0438\u0442\u0435 \u043a\u0443\u043f\u0438\u0442\u044c \u0444\u0440\u0443\u043a\u0442\u044b. \u041f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u044c\u0442\u0435, \u0447\u0442\u043e \u0432\u0441\u0435 \u0444\u0440\u0443\u043a\u0442\u044b \u0443 \u0432\u0430\u0441 \u043d\u0430\u0445\u043e\u0434\u044f\u0442\u0441\u044f \u0432 \u043e\u0434\u043d\u043e\u043c \u044f\u0449\u0438\u043a\u0435. \u0421\u043e\u0433\u043b\u0430\u0441\u0438\u0442\u0435\u0441\u044c, \u0432\u0430\u043c \u043f\u043e\u043d\u0430\u0434\u043e\u0431\u0438\u0442\u0441\u044f \u0433\u043e\u0440\u0430\u0437\u0434\u043e \u0431\u043e\u043b\u044c\u0448\u0435 \u0432\u0440\u0435\u043c\u0435\u043d\u0438, \u0447\u0442\u043e\u0431\u044b \u043d\u0430\u0439\u0442\u0438 10 \u044f\u0431\u043b\u043e\u043a. \u0411\u044b\u043b\u043e \u0431\u044b \u043f\u0440\u043e\u0449\u0435 \u0432\u0437\u044f\u0442\u044c \u044d\u0442\u0438 10 \u044f\u0431\u043b\u043e\u043a \u0438\u0437 \u043e\u0442\u0434\u0435\u043b\u044c\u043d\u043e\u0433\u043e \u044f\u0449\u0438\u043a\u0430 \u0441 \u044f\u0431\u043b\u043e\u043a\u0430\u043c\u0438. \u0422\u0430\u043a\u043e\u0439 \u0436\u0435 \u043f\u043e\u0434\u0445\u043e\u0434 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u0442\u0441\u044f \u0438 \u043f\u0440\u0438 \u0445\u0440\u0430\u043d\u0435\u043d\u0438\u0438 \u0434\u0430\u043d\u043d\u044b\u0445 \u0432 \u0442\u0430\u0431\u043b\u0438\u0446\u0430\u0445.<!--more-->\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=8XubzWm3ANY\r\n\r\n\u0412\u0441\u043f\u043e\u043c\u043d\u0438\u043c \u043f\u0440\u043e\u0448\u043b\u044b\u0439 \u0443\u0440\u043e\u043a - \u0432 \u043d\u0435\u043c \u043c\u044b \u0441\u043e\u0437\u0434\u0430\u0432\u0430\u043b\u0438 \u0442\u0430\u0431\u043b\u0438\u0446\u0443, \u0432 \u043a\u043e\u0442\u043e\u0440\u043e\u043c \u0445\u0440\u0430\u043d\u044f\u0442\u0441\u044f \u043a\u043e\u043c\u0430\u043d\u0434\u044b, \u0441\u0442\u0440\u0430\u043d\u044b \u0438 \u0438\u0433\u0440\u043e\u043a\u0438. \u042d\u0442\u043e \u0431\u044b\u043b \u043d\u0435 \u043e\u0447\u0435\u043d\u044c \u043f\u0440\u0430\u0432\u0438\u043b\u044c\u043d\u044b\u0439 \u043f\u043e\u0434\u0445\u043e\u0434 \u043a \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u0430\u0446\u0438\u0438 \u0445\u0440\u0430\u043d\u0435\u043d\u0438\u044f \u0434\u0430\u043d\u043d\u044b\u0445. \u0414\u0430\u043d\u043d\u044b\u0435 \u0432 \u0442\u0430\u043a\u043e\u0439 \u0442\u0430\u0431\u043b\u0438\u0446\u0435 \u043f\u043e\u043b\u0443\u0447\u0430\u0442\u044c \u043d\u0435\u0443\u0434\u043e\u0431\u043d\u043e \u0438 \u0447\u0430\u0441\u0442\u043e \u0437\u0430\u0442\u0440\u0430\u0442\u043d\u043e \u043f\u043e \u0432\u0440\u0435\u043c\u0435\u043d\u0438. \u0412 \u044d\u0442\u043e\u043c \u0443\u0440\u043e\u043a\u0435 \u043c\u044b \"\u0440\u0430\u0437\u0434\u0440\u043e\u0431\u0438\u043c\" \u0434\u0430\u043d\u043d\u044b\u0435 \u043d\u0430 \u0441\u0443\u0449\u043d\u043e\u0441\u0442\u0438 - \u043a\u043e\u043c\u0430\u043d\u0434\u044b, \u0438\u0433\u0440\u043e\u043a\u0438 \u0438 \u0441\u0442\u0440\u0430\u043d\u044b.\r\n\r\n\u041a\u043e\u0434 \u0443\u0440\u043e\u043a\u0430:\r\n\r\n<pre><code>create database sport;\r\nset names 'utf8';\r\nuse sport;\r\ncreate table countries ( country_id int unsigned not null primary key auto_increment, country_name varchar(255) not null );\r\ninsert into countries (country_id, country_name) values (1, '\u0420\u043e\u0441\u0441\u0438\u044f'),(null, '\u0410\u043d\u0433\u043b\u0438\u044f'),(null, '\u0418\u0441\u043f\u0430\u043d\u0438\u044f'),(null, '\u0418\u0442\u0430\u043b\u0438\u044f'), (null, '\u0413\u0435\u0440\u043c\u0430\u043d\u0438\u044f'), (null, '\u0424\u0440\u0430\u043d\u0446\u0438\u044f');\r\nSET NAMES utf8 COLLATE utf8_unicode_ci;\r\ncreate table teams ( team_id int unsigned not null primary key auto_increment, country_id int unsigned not null, team_name varchar(255), foreign key(country_id) references countries(country_id));\r\ninsert into teams (team_id, country_id, team_name) values (1, 1, '\u0426\u0421\u041a\u0410'),  (null, 2, '\u041c\u0430\u043d\u0447\u0435\u0441\u0442\u0435\u0440 \u042e\u043d\u0430\u0439\u0442\u0435\u0434'),  (null, 3, '\u0420\u0435\u0430\u043b \u041c\u0430\u0434\u0440\u0438\u0434'),  (null, 4, '\u041b\u0430\u0446\u0438\u043e'),  (null, 5, '\u0411\u0430\u0432\u0430\u0440\u0438\u044f'),  (null, 6, '\u041f\u0421\u0416');\r\ncreate table players (player_id int unsigned not null primary key auto_increment, team_id int unsigned not null, country_id int unsigned not null, player_name varchar(255), foreign key(team_id) references teams(team_id), foreign key(country_id) references countries(country_id));\r\ninsert into players (player_id, team_id, country_id, player_name) values  (1, 1, 1, '\u0418\u0433\u043e\u0440\u044c \u0410\u043a\u0438\u043d\u0444\u0435\u0435\u0432'),  (null, 3, 3, '\u041a\u0440\u0438\u0448\u0442\u0438\u0430\u043d\u0443 \u0420\u043e\u043d\u0430\u043b\u0434\u0443'),  (null, 6, 4, '\u041c\u0430\u0440\u043a\u043e \u0412\u0435\u0440\u0430\u0442\u0442\u0438');\r\ndelete from countries where country_id=3; \/*\u0417\u0430\u043f\u0440\u043e\u0441 \u0437\u0430\u0432\u0435\u0440\u0448\u0438\u0442\u0441\u044f \u043e\u0448\u0438\u0431\u043a\u043e\u0439, \u0442\u0430\u043a \u043a\u0430\u043a \u0438\u043c\u0435\u044e\u0442\u0441\u044f \u0441\u0432\u044f\u0437\u0438 \u043c\u0435\u0436\u0434\u0443 \u0442\u0430\u0431\u043b\u0438\u0446\u0430\u043c\u0438 \u043f\u043e \u0432\u043d\u0435\u0448\u043d\u0435\u043c\u0443 \u043a\u043b\u044e\u0447\u0443*\/\r\n<\/code><\/pre>","_et_gb_content_width":"","footnotes":""},"categories":[272,219],"tags":[248],"class_list":["post-3459","post","type-post","status-publish","format-standard","hentry","category-mysql","category-tutorials","tag-mysql-en"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.4 - 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Links between tables. Foreign keys - Kamil Abzalov&#039;s blog<\/title>\n<meta name=\"description\" content=\"Topic of this lesson is links between tables in mysql. You will learn about types of links between tables and foreign keys.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/kamil-abzalov.com\/videouroki\/mysql\/mysql-foreign-keys\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"MySQL. Links between tables. Foreign keys - Kamil Abzalov&#039;s blog\" \/>\n<meta property=\"og:description\" content=\"Topic of this lesson is links between tables in mysql. 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