{"id":3002,"date":"2021-01-10T13:10:08","date_gmt":"2021-01-10T05:10:08","guid":{"rendered":"https:\/\/www.gbase8.cn\/?p=3002"},"modified":"2021-01-10T16:22:05","modified_gmt":"2021-01-10T08:22:05","slug":"gbase-8a-%e6%95%b0%e7%bb%84%e9%80%89%e6%8b%a9%e5%87%bd%e6%95%b0elt%e7%9a%84%e4%bd%bf%e7%94%a8%e5%92%8c%e6%a0%b7%e4%be%8b","status":"publish","type":"post","link":"https:\/\/www.gbase8.cn\/en\/3002","title":{"rendered":"\u5357\u5927\u901a\u7528GBase 8a \u6570\u7ec4\u9009\u62e9\u51fd\u6570ELT\u548cField\u7684\u4f7f\u7528\u548c\u6837\u4f8b"},"content":{"rendered":"<p>\u672c\u6587\u4ecb\u7ecdGBase 8a\u6570\u636e\u5e93\u96c6\u7fa4\u5185\u7f6e\u51fd\u6570ELT\u548cFIELD\u7684\u4f7f\u7528\u8bed\u6cd5\u3001\u8bf4\u660e\u548c\u4f8b\u5b50\u3002\u8fd92\u4e2a\u51fd\u6570\u90fd\u662f\u4ece\u4e00\u7cfb\u5217\u5b57\u7b26\u4e32\u4e2d\u6839\u636e\u4f4d\u7f6e\u627e\u5b57\u7b26\u4e32\u6216\u8005\u6839\u636e\u5b57\u7b26\u4e32\u627e\u4f4d\u7f6e\u3002<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_84 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Directory Navigation<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-6a2a9d57ad6d3\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewbox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewbox=\"0 0 24 24\" version=\"1.2\" baseprofile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-6a2a9d57ad6d3\"  aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#ELT\" >ELT<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E8%AF%AD%E6%B3%95\" >\u8bed\u6cd5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E8%AF%B4%E6%98%8E\" >\u8bf4\u660e<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E6%A0%B7%E4%BE%8B\" >\u6837\u4f8b<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E6%AD%A3%E5%B8%B8%E6%9F%A5%E8%AF%A2\" >\u6b63\u5e38\u67e5\u8be2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E8%B6%85%E8%BF%87%E5%8F%82%E6%95%B0%E8%8C%83%E5%9B%B4\" >\u8d85\u8fc7\u53c2\u6570\u8303\u56f4<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#NULL%E5%8F%82%E6%95%B0\" >NULL\u53c2\u6570<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#FIELD\" >FIELD<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E8%AF%AD%E6%B3%95-2\" >\u8bed\u6cd5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E8%AF%B4%E6%98%8E-2\" >\u8bf4\u660e<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E6%A0%B7%E4%BE%8B-2\" >\u6837\u4f8b<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E6%AD%A3%E5%B8%B8%E6%9F%A5%E8%AF%A2-2\" >\u6b63\u5e38\u67e5\u8be2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E6%B2%A1%E6%9C%89%E6%89%BE%E5%88%B0\" >\u6ca1\u6709\u627e\u5230<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E5%8F%82%E6%95%B0%E4%B8%BANULL\" >\u53c2\u6570\u4e3aNULL<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/www.gbase8.cn\/en\/3002\/#%E5%8F%82%E8%80%83\" >\u53c2\u8003<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"ELT\"><\/span>ELT<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%AD%E6%B3%95\"><\/span>\u8bed\u6cd5<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>ELT(N,str1,str2,str3,...) <\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%B4%E6%98%8E\"><\/span>\u8bf4\u660e<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u82e5 N=1\uff0c\u5219\u8fd4\u56de\u503c\u4e3a str1\uff0c\u82e5 N=2\uff0c\u5219\u8fd4\u56de\u503c\u4e3a str2\uff0c\u4ee5\u6b64\u7c7b\u63a8\u3002<br>\u82e5 N \u5c0f\u4e8e 1 \u6216\u5927\u4e8e\u53c2\u6570\u7684\u6570\u76ee\uff0c\u5219\u8fd4\u56de\u503c\u4e3a NULL\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%A0%B7%E4%BE%8B\"><\/span>\u6837\u4f8b<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%AD%A3%E5%B8%B8%E6%9F%A5%E8%AF%A2\"><\/span>\u6b63\u5e38\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p>N=1\uff0c\u5219\u8fd4\u56de\u503c\u7b2c\u4e00\u4e2a\u5b57\u7b26\u4e32\u7684\u503c\uff0c\u4e3a str1\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>gbase&gt; SELECT ELT(1, 'ej', 'Heja', 'hej', 'foo') FROM t;\n+------------------------------------+\n| ELT(1, 'ej', 'Heja', 'hej', 'foo') |\n+------------------------------------+\n| ej                                 |\n+------------------------------------+\n1 row in set (Elapsed: 00:00:00.03)\n<\/code><\/pre>\n\n\n\n<p>N=4\uff0c\u5219\u8fd4\u56de\u503c\u4e3a str4\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>gbase&gt; SELECT ELT(4, 'ej', 'Heja', 'hej', 'foo') FROM t;\n+------------------------------------+\n| ELT(4, 'ej', 'Heja', 'hej', 'foo') |\n+------------------------------------+\n| foo                                |\n+------------------------------------+\n1 row in set (Elapsed: 00:00:00.00)\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%B6%85%E8%BF%87%E5%8F%82%E6%95%B0%E8%8C%83%E5%9B%B4\"><\/span>\u8d85\u8fc7\u53c2\u6570\u8303\u56f4<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p>\u8fd4\u56de\u503c\u4e3a NULL\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>gbase&gt; SELECT ELT(9, 'ej', 'Heja', 'hej', 'foo') FROM t;\n+------------------------------------+\n| ELT(9, 'ej', 'Heja', 'hej', 'foo') |\n+------------------------------------+\n| NULL |\n+------------------------------------+\n1 row in set\ngbase&gt; select elt(-1,1,2,3,4,5,6,7,8);\n+-------------------------+\n| elt(-1,1,2,3,4,5,6,7,8) |\n+-------------------------+\n| NULL                    |\n+-------------------------+\n1 row in set (Elapsed: 00:00:00.00)\n\ngbase&gt; select elt(null,1,2,3,4,5,6,7,8);\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"NULL%E5%8F%82%E6%95%B0\"><\/span>NULL\u53c2\u6570<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p>\u8fd4\u56deNULL<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>gbase&gt; select elt(null,1,2,3,4,5,6,7,8);\n+---------------------------+\n| elt(null,1,2,3,4,5,6,7,8) |\n+---------------------------+\n| NULL                      |\n+---------------------------+\n1 row in set (Elapsed: 00:00:00.00)\n<\/code><\/pre>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"FIELD\"><\/span>FIELD<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%AD%E6%B3%95-2\"><\/span>\u8bed\u6cd5<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>FIELD(str,str1,str2,str3,...)<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%B4%E6%98%8E-2\"><\/span>\u8bf4\u660e<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u67e5\u627e\u5b57\u7b26\u4e32\u6240\u5728\u7684\u7d22\u5f15\u4f4d\u7f6e\u3002<\/p>\n\n\n\n<p>\u5982\u679c str \u7b49\u4e8e str1 \u5219\u8fd4\u56de 1\uff0c\u5982\u679c str \u7b49\u4e8e str2 \u5219\u8fd4\u56de 2\uff0c\u4f9d\u6b21\u5411\u540e\u8fdb\u884c\u6bd4\u8f83\u3002\u90fd\u4e0d\u76f8\u7b49\u65f6\uff0c\u8fd4\u56de\u503c\u4e3a 0\u3002<br>\u5982\u679c\u6240\u6709\u5bf9\u4e8e FIELD()\u7684\u53c2\u6570\u5747\u4e3a\u5b57\u7b26\u4e32\uff0c\u5219\u6240\u6709\u53c2\u6570\u5747\u6309\u7167\u5b57\u7b26\u4e32\u8fdb\u884c\u6bd4\u8f83\u3002<br>\u5982\u679c\u6240\u6709\u7684\u53c2\u6570\u5747\u4e3a\u6570\u5b57\uff0c\u5219\u6309\u7167\u6570\u5b57\u8fdb\u884c\u6bd4\u8f83\u3002<br>\u5982\u679c str \u4e3a NULL\uff0c\u5219\u8fd4\u56de\u503c\u4e3a 0\uff0c\u539f\u56e0\u662f NULL \u4e0d\u80fd\u540c\u4efb\u4f55\u503c\u8fdb\u884c\u540c\u7b49\u6bd4\u8f83\u3002FIELD()\u662f ELT()\u7684\u8865\u6570\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%A0%B7%E4%BE%8B-2\"><\/span>\u6837\u4f8b<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%AD%A3%E5%B8%B8%E6%9F%A5%E8%AF%A2-2\"><\/span>\u6b63\u5e38\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>gbase&gt; SELECT FIELD('ej', 'ej', 'Heja', 'hej', 'foo') FROM t;\n+-----------------------------------------+\n| FIELD('ej', 'ej', 'Heja', 'hej', 'foo') |\n+-----------------------------------------+\n|                                       1 |\n+-----------------------------------------+\n1 row in set (Elapsed: 00:00:00.01)\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%B2%A1%E6%9C%89%E6%89%BE%E5%88%B0\"><\/span>\u6ca1\u6709\u627e\u5230<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p>\u8fd4\u56de\u503c\u4e3a 0\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>gbase&gt; SELECT FIELD('ej2', 'ej', 'Heja', 'hej', 'foo') FROM t;\n+------------------------------------------+\n| FIELD('ej2', 'ej', 'Heja', 'hej', 'foo') |\n+------------------------------------------+\n|                                        0 |\n+------------------------------------------+\n1 row in set (Elapsed: 00:00:00.00)\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E6%95%B0%E4%B8%BANULL\"><\/span>\u53c2\u6570\u4e3aNULL<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p>\u5373\u4f7f\u6570\u636e\u91cc\u6709NULL,\u4e5f\u662f\u8fd4\u56deNULL,\u56e0\u4e3anull\u4e0d\u80fd\u548c\u4efb\u4f55\u503c\u76f8\u7b49\u6bd4\u8f83\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>gbase&gt; SELECT FIELD(null, 'ej', 'Heja', 'hej', 'foo',null) FROM t;\n+----------------------------------------------+\n| FIELD(null, 'ej', 'Heja', 'hej', 'foo',null) |\n+----------------------------------------------+\n|                                            0 |\n+----------------------------------------------+\n1 row in set (Elapsed: 00:00:00.00)\n\n<\/code><\/pre>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E8%80%83\"><\/span>\u53c2\u8003<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>\u8bf7\u6ce8\u610f\u533a\u5206\u8be5\u51fd\u6570\u548cdecode\u51fd\u6570\u7684\u533a\u522b\u3002decode\u662f\u6210\u5bf9\u51fa\u73b0\u7684key-value\u7684\uff0c\u800celt\u66f4\u8d8b\u5411\u4e8e\u4e0b\u6807\u8bbf\u95ee\u3002<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-wp-embed is-provider-\u8001\u7d2b\u7af9\u7684\u5bb6 wp-block-embed-\u8001\u7d2b\u7af9\u7684\u5bb6\"><div class=\"wp-block-embed__wrapper\">\n<blockquote class=\"wp-embedded-content\" data-secret=\"mXCfHti3Ts\"><a href=\"https:\/\/www.gbase8.cn\/en\/2660\/\">GBase 8a\u7684DECODE\u51fd\u6570\u4f7f\u7528\u4f8b\u5b50<\/a><\/blockquote><iframe loading=\"lazy\" class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" style=\"position: absolute; clip: rect(1px, 1px, 1px, 1px);\" title=\"\u300aGBase 8a\u7684DECODE\u51fd\u6570\u4f7f\u7528\u4f8b\u5b50\u300b\u2014\u8001\u7d2b\u7af9\u7684\u5bb6\" src=\"https:\/\/www.gbase8.cn\/2660\/embed#?secret=mXCfHti3Ts\" data-secret=\"mXCfHti3Ts\" width=\"600\" height=\"338\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\"><\/iframe>\n<\/div><\/figure>\n\n\n\n<p><a href=\"https:\/\/www.gbase8.cn\/en\/2672\/\">GBase 8a\u5b57\u7b26\u4e32\u548c\u65e5\u671f\u51fd\u6570\u6c47\u603b\u5217\u8868<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>\u672c\u6587\u4ecb\u7ecdGBase 8a\u6570\u636e\u5e93\u96c6\u7fa4\u5185\u7f6e\u51fd\u6570ELT\u548cFIELD\u7684\u4f7f\u7528\u8bed\u6cd5\u3001\u8bf4\u660e\u548c\u4f8b\u5b50\u3002\u8fd92\u4e2a\u51fd\u6570\u90fd\u662f\u4ece\u4e00\u7cfb\u5217\u5b57\u7b26\u4e32\u4e2d\u6839\u636e\u4f4d\u7f6e\u627e\u5b57\u7b26\u4e32\u6216\u8005\u6839\u636e\u5b57\u7b26\u4e32\u627e\u4f4d\u7f6e<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[36],"class_list":["post-3002","post","type-post","status-publish","format-standard","hentry","category-gbase8a","tag-36"],"_links":{"self":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/3002","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/comments?post=3002"}],"version-history":[{"count":11,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/3002\/revisions"}],"predecessor-version":[{"id":3275,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/3002\/revisions\/3275"}],"wp:attachment":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/media?parent=3002"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/categories?post=3002"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/tags?post=3002"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}