{"id":9827,"date":"2024-03-14T10:13:31","date_gmt":"2024-03-14T10:13:31","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-is-the-union-operation-used-in-databases\/"},"modified":"2024-03-20T16:26:17","modified_gmt":"2024-03-20T16:26:17","slug":"how-is-the-union-operation-used-in-databases","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-is-the-union-operation-used-in-databases\/","title":{"rendered":"How is the union operation used in databases?"},"content":{"rendered":"<p>In databases, UNION is an operator used to merge the result sets of two or more SELECT statements, returning unique values. It is used to combine multiple query results into one result set, automatically removing duplicate rows.<\/p>\n<p>For example, suppose there are two tables A and B. Table A contains the fields name and age, and table B contains the fields name and gender. To query all unique values in the name fields from both tables, you can use the UNION operator.<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">SELECT<\/span> name <span class=\"hljs-keyword\">FROM<\/span> A\r\n<span class=\"hljs-keyword\">UNION<\/span>\r\n<span class=\"hljs-keyword\">SELECT<\/span> name <span class=\"hljs-keyword\">FROM<\/span> B;\r\n<\/code><\/pre>\n<p>The above query will return a collection of unique name field values from both tables. If you want to include duplicate values, you can use the UNION ALL operator.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In databases, UNION is an operator used to merge the result sets of two or more SELECT statements, returning unique values. It is used to combine multiple query results into one result set, automatically removing duplicate rows. For example, suppose there are two tables A and B. Table A contains the fields name and age, [&hellip;]<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-9827","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>How is the union operation used in databases? - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/blog\/how-is-the-union-operation-used-in-databases\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How is the union operation used in databases?\" \/>\n<meta property=\"og:description\" content=\"In databases, UNION is an operator used to merge the result sets of two or more SELECT statements, returning unique values. 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