{"id":5707,"date":"2024-11-14T11:18:44","date_gmt":"2024-11-14T03:18:44","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5707\/"},"modified":"2024-11-14T11:18:44","modified_gmt":"2024-11-14T03:18:44","slug":"sql%e6%8a%a5%e6%97%a0%e6%95%88%e6%95%b0%e5%ad%97%e6%80%8e%e4%b9%88%e8%a7%a3%e5%86%b3","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5707\/","title":{"rendered":"sql\u62a5\u65e0\u6548\u6570\u5b57\u600e\u4e48\u89e3\u51b3"},"content":{"rendered":"<blockquote><p>\n  \u8981\u89e3\u51b3 sql \u65e0\u6548\u6570\u5b57\u9519\u8bef\uff0c\u53ef\u91c7\u53d6\u4ee5\u4e0b\u6b65\u9aa4\uff1a1. \u68c0\u67e5\u6570\u636e\u7c7b\u578b\u786e\u4fdd\u5217\u6570\u636e\u7c7b\u578b\u4e0e\u63d2\u5165\u503c\u5339\u914d\u30022. \u4f7f\u7528\u9002\u5f53\u683c\u5f0f\u8f93\u5165\u6570\u5b57\uff0c\u5305\u62ec\u5c0f\u6570\u70b9\u548c\u5c0f\u6570\u4f4d\u6570\u30023. \u68c0\u67e5\u6587\u672c\u6570\u636e\u662f\u5426\u5b58\u5728\u610f\u5916\u5b57\u7b26\u6216\u7a7a\u683c\u30024. \u4f7f\u7528\u8f6c\u6362\u51fd\u6570\u5c06\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6570\u5b57\u30025. \u68c0\u67e5\u662f\u5426\u6709\u5bfc\u81f4\u9519\u8bef\u7684\u9ed8\u8ba4\u503c\u30026. \u4f7f\u7528 try_cast \u5c1d\u8bd5\u8f6c\u6362\u503c\uff0c\u5982\u679c\u8f6c\u6362\u5931\u8d25\u5219\u8fd4\u56de null\u30027. \u8003\u8651\u4f7f\u7528\u6b63\u5219\u8868\u8fbe\u5f0f\u3001\u5206\u9694\u7b26\u6216\u7b2c\u4e09\u65b9\u5e93\u6765\u5904\u7406\u6570\u5b57\u8f6c\u6362\u3002\n<\/p><\/blockquote>\n<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/202405\/30\/2024053021070110161.jpg\" class=\"aligncenter\" title=\"sql\u62a5\u65e0\u6548\u6570\u5b57\u600e\u4e48\u89e3\u51b3\u63d2\u56fe\" alt=\"sql\u62a5\u65e0\u6548\u6570\u5b57\u600e\u4e48\u89e3\u51b3\u63d2\u56fe\" \/><\/p>\n<p><strong>\u5982\u4f55\u89e3\u51b3 SQL \u4e2d\u7684\u65e0\u6548\u6570\u5b57\u9519\u8bef<\/strong><\/p>\n<p><strong>\u95ee\u9898\uff1a<\/strong>\u5982\u4f55\u89e3\u51b3 SQL \u4e2d\u7684\u65e0\u6548\u6570\u5b57\u9519\u8bef\uff1f<\/p>\n<p><strong>\u56de\u7b54\uff1a<\/strong>\u8981\u89e3\u51b3 SQL \u4e2d\u7684\u65e0\u6548\u6570\u5b57\u9519\u8bef\uff0c\u60a8\u53ef\u4ee5\u91c7\u53d6\u4ee5\u4e0b\u6b65\u9aa4\uff1a<\/p>\n<p><strong>1. \u68c0\u67e5\u6570\u636e\u7c7b\u578b<\/strong><\/p>\n<p>\u786e\u4fdd\u6570\u636e\u5217\u7684\u6570\u636e\u7c7b\u578b\u4e0e\u8981\u63d2\u5165\u7684\u503c\u7684\u6570\u636e\u7c7b\u578b\u76f8\u5339\u914d\u3002\u4f8b\u5982\uff0c\u5982\u679c\u5217\u7684\u6570\u636e\u7c7b\u578b\u4e3a\u6574\u6570\uff0c\u5219\u4e0d\u80fd\u63d2\u5165\u6d6e\u70b9\u6570\u3002<\/p>\n<p><strong>2. \u4f7f\u7528\u9002\u5f53\u7684\u683c\u5f0f<\/strong><\/p>\n<p>\u4f7f\u7528\u6b63\u786e\u7684\u683c\u5f0f\u8f93\u5165\u6570\u5b57\uff0c\u5305\u62ec\u5c0f\u6570\u70b9\u548c\u5c0f\u6570\u4f4d\u6570\u3002\u4f8b\u5982\uff0c\u5c06\u6d6e\u70b9\u6570 1.2345 \u63d2\u5165\u5341\u8fdb\u5236(10,5)\u5217\u65f6\uff0c\u5e94\u4f7f\u7528 &#8216;1.23450&#8217;\u3002<\/p>\n<p><strong>3. \u68c0\u67e5\u6587\u672c\u6570\u636e<\/strong><\/p>\n<p>\u5982\u679c\u6570\u636e\u5217\u662f\u6587\u672c\u7c7b\u578b\uff0c\u5219\u786e\u4fdd\u6ca1\u6709\u610f\u5916\u7684\u5b57\u7b26\u6216\u7a7a\u683c\u3002\u8fd9\u4e9b\u5b57\u7b26\u53ef\u80fd\u4f1a\u5bfc\u81f4\u65e0\u6548\u6570\u5b57\u9519\u8bef\u3002<\/p>\n<p><strong>4. \u4f7f\u7528\u8f6c\u6362\u51fd\u6570<\/strong><\/p>\n<p>\u53ef\u4ee5\u4f7f\u7528\u8f6c\u6362\u51fd\u6570\u5c06\u5b57\u7b26\u4e32\u503c\u8f6c\u6362\u4e3a\u6570\u5b57\u3002\u4f8b\u5982\uff0c\u5728\u63d2\u5165\u5b57\u7b26\u4e32 &#8216;123.45&#8217; \u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u51fd\u6570\u5c06\u5176\u8f6c\u6362\u4e3a\u6570\u5b57\uff1a<\/p>\n<pre>CAST('123.45' AS FLOAT)<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>5. \u68c0\u67e5\u9ed8\u8ba4\u503c<\/strong><\/p>\n<p>\u68c0\u67e5\u5217\u662f\u5426\u6709\u9ed8\u8ba4\u503c\u3002\u5982\u679c\u9ed8\u8ba4\u503c\u4e3a\u65e0\u6548\u6570\u5b57\uff0c\u5219\u4f1a\u5f15\u53d1\u9519\u8bef\u3002<\/p>\n<p><strong>6. \u4f7f\u7528 TRY_CAST<\/strong><\/p>\n<p>\u53ef\u4ee5\u5c1d\u8bd5\u4f7f\u7528 TRY_CAST \u51fd\u6570\u6765\u8f6c\u6362\u503c\u3002\u5982\u679c\u8f6c\u6362\u6210\u529f\uff0c\u5219 TRY_CAST \u8fd4\u56de\u8f6c\u6362\u540e\u7684\u503c\uff0c\u5426\u5219\u8fd4\u56de NULL\u3002<\/p>\n<pre>TRY_CAST('123.45' AS FLOAT)<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p><strong>7. \u5176\u4ed6\u65b9\u6cd5<\/strong><\/p>\n<ul>\n<li>\u4f7f\u7528\u6b63\u5219\u8868\u8fbe\u5f0f\u9a8c\u8bc1\u503c\u662f\u5426\u4e3a\u6570\u5b57\u3002<\/li>\n<li>\u4f7f\u7528\u5206\u9694\u7b26\u5c06\u503c\u8f6c\u6362\u4e3a\u6570\u5b57\u3002<\/li>\n<li>\u4f7f\u7528\u7b2c\u4e09\u65b9\u5e93\u6216\u5de5\u5177\u6765\u5904\u7406\u6570\u5b57\u8f6c\u6362\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0a\u5c31\u662fsql\u62a5\u65e0\u6548\u6570\u5b57\u600e\u4e48\u89e3\u51b3\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>\u8981\u89e3\u51b3 sql \u65e0\u6548\u6570\u5b57\u9519\u8bef\uff0c\u53ef\u91c7\u53d6\u4ee5\u4e0b\u6b65\u9aa4\uff1a1. \u68c0\u67e5\u6570\u636e\u7c7b\u578b\u786e\u4fdd\u5217\u6570\u636e\u7c7b\u578b\u4e0e\u63d2\u5165\u503c\u5339\u914d\u30022. \u4f7f\u7528\u9002\u5f53\u683c\u5f0f\u8f93\u5165\u6570\u5b57\uff0c\u5305\u62ec\u5c0f\u6570\u70b9\u548c\u5c0f\u6570\u4f4d\u6570\u30023. \u68c0\u67e5\u6587\u672c\u6570\u636e\u662f\u5426\u5b58\u5728\u610f\u5916\u5b57\u7b26\u6216\u7a7a\u683c\u30024. \u4f7f\u7528\u8f6c\u6362\u51fd\u6570\u5c06\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6570\u5b57\u30025. \u68c0\u67e5\u662f\u5426\u6709\u5bfc\u81f4\u9519\u8bef\u7684\u9ed8\u8ba4\u503c\u30026. \u4f7f\u7528 try_cast \u5c1d\u8bd5\u8f6c\u6362\u503c\uff0c\u5982\u679c\u8f6c\u6362\u5931\u8d25\u5219\u8fd4\u56de null\u30027. \u8003\u8651\u4f7f\u7528\u6b63\u5219\u8868\u8fbe\u5f0f\u3001\u5206\u9694\u7b26\u6216\u7b2c\u4e09\u65b9\u5e93\u6765\u5904\u7406\u6570\u5b57\u8f6c\u6362\u3002 \u5982\u4f55\u89e3\u51b3 SQL \u4e2d\u7684\u65e0\u6548\u6570\u5b57\u9519\u8bef \u95ee\u9898\uff1a\u5982\u4f55\u89e3\u51b3 SQL \u4e2d\u7684\u65e0\u6548\u6570\u5b57\u9519\u8bef\uff1f \u56de\u7b54\uff1a\u8981\u89e3\u51b3 SQL \u4e2d\u7684\u65e0\u6548\u6570\u5b57\u9519\u8bef\uff0c\u60a8\u53ef\u4ee5\u91c7\u53d6\u4ee5\u4e0b\u6b65\u9aa4\uff1a 1. \u68c0\u67e5\u6570\u636e\u7c7b\u578b \u786e\u4fdd\u6570\u636e\u5217\u7684\u6570\u636e\u7c7b\u578b\u4e0e\u8981\u63d2\u5165\u7684\u503c\u7684\u6570\u636e\u7c7b\u578b\u76f8\u5339\u914d\u3002\u4f8b\u5982\uff0c\u5982\u679c\u5217\u7684\u6570\u636e\u7c7b\u578b\u4e3a\u6574\u6570\uff0c\u5219\u4e0d\u80fd\u63d2\u5165\u6d6e\u70b9\u6570\u3002 2. \u4f7f\u7528\u9002\u5f53\u7684\u683c\u5f0f \u4f7f\u7528\u6b63\u786e\u7684\u683c\u5f0f\u8f93\u5165\u6570\u5b57\uff0c\u5305\u62ec\u5c0f\u6570\u70b9\u548c\u5c0f\u6570\u4f4d\u6570\u3002\u4f8b\u5982\uff0c\u5c06\u6d6e\u70b9\u6570 1.2345 \u63d2\u5165\u5341\u8fdb\u5236(10,5)\u5217\u65f6\uff0c\u5e94\u4f7f\u7528 &#8216;1.23450&#8217;\u3002 3. \u68c0\u67e5\u6587\u672c\u6570\u636e \u5982\u679c\u6570\u636e\u5217\u662f\u6587\u672c\u7c7b\u578b\uff0c\u5219\u786e\u4fdd\u6ca1\u6709\u610f\u5916\u7684\u5b57\u7b26\u6216\u7a7a\u683c\u3002\u8fd9\u4e9b\u5b57\u7b26\u53ef\u80fd\u4f1a\u5bfc\u81f4\u65e0\u6548\u6570\u5b57\u9519\u8bef\u3002 4. \u4f7f\u7528\u8f6c\u6362\u51fd\u6570 \u53ef\u4ee5\u4f7f\u7528\u8f6c\u6362\u51fd\u6570\u5c06\u5b57\u7b26\u4e32\u503c\u8f6c\u6362\u4e3a\u6570\u5b57\u3002\u4f8b\u5982\uff0c\u5728\u63d2\u5165\u5b57\u7b26\u4e32 &#8216;123.45&#8217; \u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u51fd\u6570\u5c06\u5176\u8f6c\u6362\u4e3a\u6570\u5b57\uff1a CAST(&#8216;123.45&#8217; AS FLOAT) \u767b\u5f55\u540e\u590d\u5236 5. \u68c0\u67e5\u9ed8\u8ba4\u503c \u68c0\u67e5\u5217\u662f\u5426\u6709\u9ed8\u8ba4\u503c\u3002\u5982\u679c\u9ed8\u8ba4\u503c\u4e3a\u65e0\u6548\u6570\u5b57\uff0c\u5219\u4f1a\u5f15\u53d1\u9519\u8bef\u3002 6. \u4f7f\u7528 TRY_CAST \u53ef\u4ee5\u5c1d\u8bd5\u4f7f\u7528 TRY_CAST \u51fd\u6570\u6765\u8f6c\u6362\u503c\u3002\u5982\u679c\u8f6c\u6362\u6210\u529f\uff0c\u5219 TRY_CAST \u8fd4\u56de\u8f6c\u6362\u540e\u7684\u503c\uff0c\u5426\u5219\u8fd4\u56de NULL\u3002 [&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-5707","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5707","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=5707"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5707\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5707"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5707"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5707"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}