{"id":5905,"date":"2024-11-14T12:43:05","date_gmt":"2024-11-14T04:43:05","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5905\/"},"modified":"2024-11-14T12:43:05","modified_gmt":"2024-11-14T04:43:05","slug":"sql%e4%b8%89%e8%a1%a8%e5%85%b3%e8%81%94%e6%9f%a5%e8%af%a2%e6%80%8e%e4%b9%88%e6%9f%a5","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5905\/","title":{"rendered":"sql\u4e09\u8868\u5173\u8054\u67e5\u8be2\u600e\u4e48\u67e5"},"content":{"rendered":"<blockquote><p>\n  sql \u4e09\u8868\u5173\u8054\u67e5\u8be2\u6d89\u53ca\u4ee5\u4e0b\u6b65\u9aa4\uff1a\u9009\u62e9\u8868\u8fde\u63a5\u7c7b\u578b\uff08inner join\u3001left join\u3001right join\u3001full join\uff09\u4f7f\u7528 on \u5173\u952e\u5b57\u6307\u5b9a\u5173\u8054\u6761\u4ef6\uff08\u5de6\u8868\u5b57\u6bb5 = \u53f3\u8868\u5b57\u6bb5\uff09\u4f7f\u7528\u4ee5\u4e0b\u8bed\u6cd5\u6267\u884c\u67e5\u8be2\uff1aselect from on on\n<\/p><\/blockquote>\n<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/202406\/03\/2024060322062360160.jpg\" class=\"aligncenter\" title=\"sql\u4e09\u8868\u5173\u8054\u67e5\u8be2\u600e\u4e48\u67e5\u63d2\u56fe\" alt=\"sql\u4e09\u8868\u5173\u8054\u67e5\u8be2\u600e\u4e48\u67e5\u63d2\u56fe\" \/><\/p>\n<p><strong>\u5982\u4f55\u6267\u884c SQL \u4e09\u8868\u5173\u8054\u67e5\u8be2\uff1f<\/strong><\/p>\n<p>\u5173\u8054\u67e5\u8be2\u7528\u4e8e\u4ece\u591a\u4e2a\u8868\u4e2d\u5408\u5e76\u6570\u636e\u3002\u4f7f\u7528 SQL \u8fdb\u884c\u4e09\u8868\u5173\u8054\u67e5\u8be2\u9700\u8981\u4ee5\u4e0b\u6b65\u9aa4\uff1a<\/p>\n<p><strong>1. \u8868\u8fde\u63a5\u7c7b\u578b\uff1a<\/strong><\/p>\n<p>\u9009\u62e9\u4e0e\u60a8\u5173\u8054\u9700\u6c42\u76f8\u5bf9\u5e94\u7684\u8fde\u63a5\u7c7b\u578b\uff1a<\/p>\n<ul>\n<li> <strong>INNER JOIN\uff1a<\/strong>\u4ec5\u8fd4\u56de\u4e24\u4e2a\u8868\u7684\u516c\u5171\u884c\u3002<\/li>\n<li> <strong>LEFT JOIN\uff1a<\/strong>\u8fd4\u56de\u5de6\u8868\u7684\u6240\u6709\u884c\u4ee5\u53ca\u5339\u914d\u53f3\u8868\u7684\u884c\uff0c\u5982\u679c\u6ca1\u6709\u5339\u914d\u9879\uff0c\u5219\u8fd4\u56de NULL\u3002<\/li>\n<li> <strong>RIGHT JOIN\uff1a<\/strong>\u8fd4\u56de\u53f3\u8868\u7684\u6240\u6709\u884c\u4ee5\u53ca\u5339\u914d\u5de6\u8868\u7684\u884c\uff0c\u5982\u679c\u6ca1\u6709\u5339\u914d\u9879\uff0c\u5219\u8fd4\u56de NULL\u3002<\/li>\n<li> <strong>FULL JOIN\uff1a<\/strong>\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u6ca1\u6709\u5339\u914d\u9879\u3002<\/li>\n<\/ul>\n<p><strong>2. \u5173\u8054\u6761\u4ef6\uff1a<\/strong><\/p>\n<p>\u6307\u5b9a\u8fde\u63a5\u8868\u4e4b\u95f4\u7684\u5173\u8054\u6761\u4ef6\uff0c\u901a\u5e38\u4f7f\u7528 ON \u5173\u952e\u5b57\uff1a<\/p>\n<pre>ON &lt;\u5de6\u8868\u5b57\u6bb5&gt; = &lt;\u53f3\u8868\u5b57\u6bb5&gt;<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>3. \u67e5\u8be2\u8bed\u6cd5\uff1a<\/strong><\/p>\n<p>\u4f7f\u7528\u4ee5\u4e0b\u8bed\u6cd5\u6267\u884c\u5173\u8054\u67e5\u8be2\uff1a<\/p>\n<pre>SELECT &lt;\u5217\u5217\u8868&gt;\nFROM &lt;\u88681&gt;\n&lt;\u8fde\u63a5\u7c7b\u578b&gt; &lt;\u88682&gt; ON &lt;\u5173\u8054\u6761\u4ef6&gt;\n&lt;\u8fde\u63a5\u7c7b\u578b&gt; &lt;\u88683&gt; ON &lt;\u5173\u8054\u6761\u4ef6&gt;<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>\u793a\u4f8b\uff1a<\/strong><\/p>\n<p>\u5047\u8bbe\u6211\u4eec\u6709\u4ee5\u4e0b\u4e09\u4e2a\u8868\uff1a<\/p>\n<ul>\n<li> <strong>\u5ba2\u6237\u8868 (Customers)\uff1a<\/strong>id, name, city<\/li>\n<li> <strong>\u8ba2\u5355\u8868 (Orders)\uff1a<\/strong>id, customer_id, product_id, quantity<\/li>\n<li> <strong>\u4ea7\u54c1\u8868 (Products)\uff1a<\/strong>id, name, price<\/li>\n<\/ul>\n<p>\u8981\u67e5\u627e\u67d0\u4e2a\u5ba2\u6237\u7684\u6240\u6709\u8ba2\u5355\u4ee5\u53ca\u4ea7\u54c1\u4fe1\u606f\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8be2\uff1a<\/p>\n<pre>SELECT\n  Customers.name AS CustomerName,\n  Products.name AS ProductName,\n  Orders.quantity\nFROM Customers\nINNER JOIN Orders ON Customers.id = Orders.customer_id\nINNER JOIN Products ON Orders.product_id = Products.id\nWHERE Customers.name = 'John Doe';<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>\u6ce8\u610f\u4e8b\u9879\uff1a<\/strong><\/p>\n<ul>\n<li>\u786e\u4fdd\u8fde\u63a5\u5b57\u6bb5\u7684\u6570\u636e\u7c7b\u578b\u76f8\u540c\u3002<\/li>\n<li>\u5982\u679c\u5b58\u5728\u591a\u4e2a\u5173\u8054\u6761\u4ef6\uff0c\u53ef\u4ee5\u4f7f\u7528\u62ec\u53f7\u5c06\u5176\u5206\u7ec4\u3002<\/li>\n<li>\u60a8\u8fd8\u53ef\u4ee5\u4f7f\u7528 USING \u5173\u952e\u5b57\u6307\u5b9a\u8fde\u63a5\u5b57\u6bb5\uff08\u9002\u7528\u4e8e\u591a\u4e2a\u516c\u5171\u5b57\u6bb5\uff09\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0a\u5c31\u662fsql\u4e09\u8868\u5173\u8054\u67e5\u8be2\u600e\u4e48\u67e5\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>sql \u4e09\u8868\u5173\u8054\u67e5\u8be2\u6d89\u53ca\u4ee5\u4e0b\u6b65\u9aa4\uff1a\u9009\u62e9\u8868\u8fde\u63a5\u7c7b\u578b\uff08inner join\u3001left join\u3001right join\u3001full join\uff09\u4f7f\u7528 on \u5173\u952e\u5b57\u6307\u5b9a\u5173\u8054\u6761\u4ef6\uff08\u5de6\u8868\u5b57\u6bb5 = \u53f3\u8868\u5b57\u6bb5\uff09\u4f7f\u7528\u4ee5\u4e0b\u8bed\u6cd5\u6267\u884c\u67e5\u8be2\uff1aselect from on on \u5982\u4f55\u6267\u884c SQL \u4e09\u8868\u5173\u8054\u67e5\u8be2\uff1f \u5173\u8054\u67e5\u8be2\u7528\u4e8e\u4ece\u591a\u4e2a\u8868\u4e2d\u5408\u5e76\u6570\u636e\u3002\u4f7f\u7528 SQL \u8fdb\u884c\u4e09\u8868\u5173\u8054\u67e5\u8be2\u9700\u8981\u4ee5\u4e0b\u6b65\u9aa4\uff1a 1. \u8868\u8fde\u63a5\u7c7b\u578b\uff1a \u9009\u62e9\u4e0e\u60a8\u5173\u8054\u9700\u6c42\u76f8\u5bf9\u5e94\u7684\u8fde\u63a5\u7c7b\u578b\uff1a INNER JOIN\uff1a\u4ec5\u8fd4\u56de\u4e24\u4e2a\u8868\u7684\u516c\u5171\u884c\u3002 LEFT JOIN\uff1a\u8fd4\u56de\u5de6\u8868\u7684\u6240\u6709\u884c\u4ee5\u53ca\u5339\u914d\u53f3\u8868\u7684\u884c\uff0c\u5982\u679c\u6ca1\u6709\u5339\u914d\u9879\uff0c\u5219\u8fd4\u56de NULL\u3002 RIGHT JOIN\uff1a\u8fd4\u56de\u53f3\u8868\u7684\u6240\u6709\u884c\u4ee5\u53ca\u5339\u914d\u5de6\u8868\u7684\u884c\uff0c\u5982\u679c\u6ca1\u6709\u5339\u914d\u9879\uff0c\u5219\u8fd4\u56de NULL\u3002 FULL JOIN\uff1a\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u6ca1\u6709\u5339\u914d\u9879\u3002 2. \u5173\u8054\u6761\u4ef6\uff1a \u6307\u5b9a\u8fde\u63a5\u8868\u4e4b\u95f4\u7684\u5173\u8054\u6761\u4ef6\uff0c\u901a\u5e38\u4f7f\u7528 ON \u5173\u952e\u5b57\uff1a ON &lt;\u5de6\u8868\u5b57\u6bb5&gt; = &lt;\u53f3\u8868\u5b57\u6bb5&gt; \u767b\u5f55\u540e\u590d\u5236 3. \u67e5\u8be2\u8bed\u6cd5\uff1a \u4f7f\u7528\u4ee5\u4e0b\u8bed\u6cd5\u6267\u884c\u5173\u8054\u67e5\u8be2\uff1a SELECT &lt;\u5217\u5217\u8868&gt; FROM &lt;\u88681&gt; &lt;\u8fde\u63a5\u7c7b\u578b&gt; &lt;\u88682&gt; ON &lt;\u5173\u8054\u6761\u4ef6&gt; &lt;\u8fde\u63a5\u7c7b\u578b&gt; &lt;\u88683&gt; [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-5905","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5905","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=5905"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5905\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5905"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5905"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5905"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}