{"id":3437,"date":"2016-03-16T12:35:59","date_gmt":"2016-03-16T12:35:59","guid":{"rendered":"http:\/\/www.garysieling.com\/blog\/?p=3437"},"modified":"2016-03-16T12:35:59","modified_gmt":"2016-03-16T12:35:59","slug":"rethinkdb-inner-join-example","status":"publish","type":"post","link":"https:\/\/www.garysieling.com\/blog\/rethinkdb-inner-join-example\/","title":{"rendered":"RethinkDB: INNER JOIN Example"},"content":{"rendered":"<p>One way to to do an inner join in RethinkDB with the eqJoin function:<\/p>\n<pre lang=\"javascript\">r.db('test')\n .table('user_actions')\n .filter({file_name: 'test2.pdf'})\n .eqJoin('user_id', r.table('users'))\n<\/pre>\n<p>The biggest disadvantage to this API is that you can&#8217;t easily reverse the order of the tables. In this case, I&#8217;m taking users and adding audit information to them, and in SQL I would be inclined to reverse the order of the join. While this is functionally identical, you may find cases where this forces you to think differently about the process.<\/p>\n<pre lang=\"javascript\">{\n  \"left\": {\n    \"action\":  \"open file\" ,\n    \"file_name\":  \"test2.pdf\" ,\n    \"id\":  \"07123881-5d95-4596-b0b4-3b1f50860bfe\" ,\n    \"user_id\":  \"450e77d6-d5c6-4533-b2d7-c0158bb097c9\"\n  } ,\n  \"right\": {\n    \"first_name\":  \"test\" ,\n    \"id\":  \"450e77d6-d5c6-4533-b2d7-c0158bb097c9\" ,\n    \"work_history\": [\n      {\n        \"role\":  \"role 1\"\n      },\n      {\n        \"role\":  \"role 2\"\n      }\n    ]\n  }\n}<\/pre>\n<p>Note that the above result makes objects called &#8220;left&#8221; and &#8220;right&#8221; in the result, which is not typically what you&#8217;d want &#8211; you can fix this by adding .zip:<\/p>\n<pre lang=\"javascript\">\nr.db('test')\n .table('user_actions')\n .filter({file_name: 'test2.pdf'})\n .eqJoin('user_id', r.table('users'))\n .zip()\n<\/pre>\n<p>The other way to do this is with &#8220;innerJoin&#8221; which requires more effort, but is more flexible and lets you write things that are exact equivalences to SQL:<\/p>\n<pre lang=\"javascript\">\nr.db('test')\n .table('user_actions')\n .filter({file_name: 'test2.pdf'})\n .innerJoin(r.table('users'),\n    (action, user) => \n      action('user_id').eq(user('id')))\n<\/pre>\n<p>And this is the final output:<\/p>\n<pre lang=\"javascript\">\n{\n  \"action\":  \"open file\" ,\n  \"file_name\":  \"test2.pdf\" ,\n  \"first_name\":  \"test\" ,\n  \"id\":  \"450e77d6-d5c6-4533-b2d7-c0158bb097c9\" ,\n  \"user_id\":  \"450e77d6-d5c6-4533-b2d7-c0158bb097c9\" ,\n  \"work_history\": [\n    {\n      \"role\":  \"role 1\"\n    } ,\n    {\n      \"role\":  \"role 2\"\n    }\n  ]\n}\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>One way to to do an inner join in RethinkDB with the eqJoin function: r.db(&#8216;test&#8217;) .table(&#8216;user_actions&#8217;) .filter({file_name: &#8216;test2.pdf&#8217;}) .eqJoin(&#8216;user_id&#8217;, r.table(&#8216;users&#8217;)) The biggest disadvantage to this API is that you can&#8217;t easily reverse the order of the tables. In this case, I&#8217;m taking users and adding audit information to them, and in SQL I would be &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/www.garysieling.com\/blog\/rethinkdb-inner-join-example\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;RethinkDB: INNER JOIN Example&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[4],"tags":[160,302,462,466,523],"aioseo_notices":[],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/posts\/3437"}],"collection":[{"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/comments?post=3437"}],"version-history":[{"count":0,"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/posts\/3437\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/media?parent=3437"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/categories?post=3437"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.garysieling.com\/blog\/wp-json\/wp\/v2\/tags?post=3437"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}