{"id":1816,"date":"2015-04-19T09:58:06","date_gmt":"2015-04-19T01:58:06","guid":{"rendered":"http:\/\/www.821121.com\/?p=1816"},"modified":"2022-10-18T10:07:22","modified_gmt":"2022-10-18T02:07:22","slug":"oracle-sql-%e4%b9%8b%e6%95%b0%e6%8d%ae%e8%bd%ac%e6%8d%a2","status":"publish","type":"post","link":"http:\/\/www.821121.com\/?p=1816","title":{"rendered":"Oracle SQL \u4e4b\u6570\u636e\u8f6c\u6362"},"content":{"rendered":"<h3>1.\u5728 Oracle SQL \u4e2d\u8f6c\u6362\u4e3a\u6570\u5b57<\/h3>\n<p>\u53ef\u4ee5\u4f7f\u7528CAST\u51fd\u6570\u6216TO_NUMBER\u51fd\u6570\u3002<\/p>\n<p>CAST \u548c TO_NUMBER \u4e4b\u95f4\u7684\u4e3b\u8981\u533a\u522b\u5728\u4e8e CAST\u7b26\u5408 ANSI\uff0c\u800cTO<em>NUMBER\uff08\u8fde\u540c\u5176\u4ed6 TO<\/em>* \u51fd\u6570\uff09\u662f Oracle \u7279\u5b9a\u7684\u3002CAST \u8fd8\u9002\u7528\u4e8e\u66f4\u5e7f\u6cdb\u7684\u6570\u636e\u7c7b\u578b\u3002<\/p>\n<p>TO_NUMBER \u5141\u8bb8\u60a8\u5c06\u5b57\u7b26\u4e32\uff08VARCHAR2\u3001CHAR \u7b49\uff09\u8f6c\u6362\u4e3a NUMBER \u7c7b\u578b\u3002<\/p>\n<pre><code>TO_NUMBER(value)<\/code><\/pre>\n<h4>\u6570\u5b57\u8f6c\u6362\u5b9e\u4f8b\uff1a<\/h4>\n<p>TO_NUMBER \u51fd\u6570,\u5b83\u6709\u4e00\u4e2a\u53c2\u6570\u2014\u2014\u8981\u8f6c\u6362\u7684\u503c\u3002\u5b83\u63a5\u53d7\u4e00\u79cd\u5b57\u7b26\u4e32\u7c7b\u578b\uff0c\u5e76\u8fd4\u56de\u4e00\u4e2a NUMBER \u6570\u636e\u7c7b\u578b\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-shell\">TO_NUMBER(&#039;150&#039;)<\/code><\/pre>\n<p>\u6b64\u51fd\u6570\u5c06\u8fd4\u56de\u4e00\u4e2a\u6570\u5b57\u503c 150\u3002<\/p>\n<p>\u8fd8\u6709 TO_BINARY_DOUBLE \u548c TO_BINARY_FLOAT \u51fd\u6570\uff0c\u5b83\u4eec\u5206\u522b\u5c06\u503c\u8f6c\u6362\u4e3a BINARY DOUBLE \u548c BINARY FLOAT \u6570\u636e\u7c7b\u578b\u3002<\/p>\n<h3>2.\u5728 Oracle SQL \u4e2d\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32<\/h3>\n<p>\u4e0e NUMBER \u6570\u636e\u7c7b\u578b\u4e00\u6837\uff0c\u6709\u4e24\u79cd\u65b9\u6cd5\u53ef\u4ee5\u5c06\u503c\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\u3002<\/p>\n<p>Oracle\u4e2d\u4e3b\u8981\u7684\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\u6709\uff1a<\/p>\n<p>\u5b57\u7b26<br \/>\nNCHAR<br \/>\nVARCHAR2<br \/>\nNVARCHAR2<br \/>\n\u6587\u672c<\/p>\n<p>TO_CHAR \u51fd\u6570\u63a5\u53d7\u4e00\u4e2a\u503c\u5e76\u5c06\u5176\u8f6c\u6362\u4e3a TEXT \u6570\u636e\u7c7b\u578b\u3002\u5b83\u7684\u5de5\u4f5c\u65b9\u5f0f\u4e0e TO_NUMBER \u7c7b\u4f3c\uff0c\u4f46\u6709\u4e00\u4e9b\u53c2\u6570\u3002<\/p>\n<pre><code>TO_CHAR(expression, [format,] [options])<\/code><\/pre>\n<p>\u8868\u8fbe\u5f0f\u662f\u8981\u8f6c\u6362\u4e3a TEXT \u6570\u636e\u7c7b\u578b\u7684\u503c\uff0c\u53ef\u4ee5\u662f\u65e5\u671f\u3001\u6570\u5b57\u6216 NTEXT \u7c7b\u578b\u3002\u683c\u5f0f\u662f\u8bc6\u522b\u6216\u683c\u5f0f\u5316\u8f93\u5165\u6570\u636e\u7684\u65b9\u5f0f\uff0c\u9009\u9879\u6307\u5b9a\u8bed\u8a00\u6216\u8d27\u5e01\u4fe1\u606f\u3002<\/p>\n<p>\u5728\u5927\u591a\u6570\u60c5\u51b5\u4e0b\uff0c\u53ea\u9700\u8981\u7b2c\u4e00\u4e2a\u53c2\u6570\uff0c\u8fd9\u662f\u552f\u4e00\u9700\u8981\u7684\u53c2\u6570\u3002<\/p>\n<h4>\u5b57\u7b26\u8f6c\u6362\u5b9e\u4f8b\uff1a<\/h4>\n<pre><code>TO_CHAR(&#039;20-JAN-2015&#039;)<\/code><\/pre>\n<p>\u8fd9\u5c06\u4ee5 TEXT \u6570\u636e\u7c7b\u578b\u663e\u793a\u65e5\u671f\u3002<\/p>\n<pre><code>TO_CHAR(1342)<\/code><\/pre>\n<p>\u8fd9\u5c06\u4ee5 TEXT \u6570\u636e\u7c7b\u578b\u663e\u793a\u6570\u5b57\u3002<\/p>\n<p>\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\u7684\u53e6\u4e00\u79cd\u65b9\u6cd5\u662f\u4f7f\u7528 CAST\u3002\u5b83\u53ef\u4ee5\u8f6c\u6362\u4e3a\u66f4\u591a\u7684\u6570\u636e\u7c7b\u578b\uff1a<\/p>\n<p>\u5b57\u7b26<br \/>\nVARCHAR2<br \/>\nNCHAR<br \/>\nNVARCHAR2<br \/>\nCAST \u51fd\u6570\u5177\u6709\u4e0e\u524d\u9762\u63d0\u5230\u7684\u76f8\u540c\u7684\u53c2\u6570\u3002<\/p>\n<h3>3.\u5728 Oracle SQL \u4e2d\u8f6c\u6362\u4e3a\u65e5\u671f<\/h3>\n<p>\u5c31\u50cf\u6570\u5b57\u548c\u5b57\u7b26\u4e32\u7c7b\u578b\u4e00\u6837\uff0c\u6709\u4e24\u79cd\u65b9\u6cd5\u53ef\u4ee5\u8f6c\u6362\u4e3a\u65e5\u671f\u7c7b\u578b\u3002<\/p>\n<p>\u4f46\u662f\uff0c\u5728 Oracle \u4e2d\uff0c\u6709\u4e24\u79cd\u4e3b\u8981\u7684\u6570\u636e\u7c7b\u578b\u7528\u4e8e\u5b58\u50a8\u65e5\u671f\uff1a<\/p>\n<p>DATE \u2013 \u5b58\u50a8\u65e5\u3001\u6708\u3001\u5e74\u3001\u5c0f\u65f6\u3001\u5206\u949f\u548c\u79d2\u3002<br \/>\nTIMESTAMP \u2013 \u5b58\u50a8\u65e5\u3001\u6708\u3001\u5e74\u3001\u5c0f\u65f6\u3001\u5206\u949f\u3001\u79d2\u548c\u79d2\u7684\u5c0f\u6570\u90e8\u5206<\/p>\n<p>\u8981\u4ec5\u8f6c\u6362\u4e3a DATE\uff0c\u53ef\u4ee5\u4f7f\u7528TO_DATE \u51fd\u6570\u3002\u5b83\u9700\u8981\u51e0\u4e2a\u53c2\u6570\uff1a<\/p>\n<pre><code>TO_DATE(string, [format,] [nls_parameters])<\/code><\/pre>\n<p>\u5b57\u7b26\u4e32\u662f\u8981\u8f6c\u6362\u7684\u503c\uff0c\u5e76\u4e14\u662f\u552f\u4e00\u5fc5\u9700\u7684\u53c2\u6570\u3002\u683c\u5f0f\u662f\u5b58\u50a8\u4e3a\u5b57\u7b26\u4e32\u7684\u65e5\u671f\u683c\u5f0f\uff0cnls_parameters \u6307\u5b9a\u8bed\u8a00\u6216\u533a\u57df\u8bbe\u7f6e\u3002<\/p>\n<h4>\u65e5\u671f\u8f6c\u6362\u5b9e\u4f8b\uff1a<\/h4>\n<p>TO_DATE('18-APR-2015')<br \/>\n\u8fd9\u4f1a\u5c06\u5b57\u7b26\u4e32\u4e2d\u7684\u503c\u8f6c\u6362\u4e3a DATE \u7c7b\u578b\u3002<br \/>\n\u4f7f\u7528\u53c2\u6570\uff0c\u53ef\u4ee5\u6307\u5b9a\u4e0d\u540c\u7c7b\u578b\u7684\u65e5\u671f\u3002<\/p>\n<p>TO_DATE('01\/02\/2015', 'dd\/mm\/yyyy')<br \/>\n\u8fd9\u4f1a\u5c06\u65e5\u671f\u6307\u5b9a\u4e3a\u60a8\u63d0\u5230\u7684\u683c\u5f0f\uff0c\u5e76\u5c06\u5176\u8f6c\u6362\u4e3a\u65e5\u671f\u3002<\/p>\n<p>\u5982\u679c\u8981\u8f6c\u6362\u4e3a\u65e5\u671f\u548c\u65f6\u95f4\u6216 TIMESTAMP\uff0c\u5219\u53ef\u4ee5\u4f7f\u7528 TO_TIMESTAMP \u51fd\u6570\u3002<\/p>\n<pre><code>TO_TIMESTAMP(string, [format,] [nls_parameters])<\/code><\/pre>\n<p>TO_TIMESTAMP('10-MAR-2015 13:06:10')<br \/>\n\u8fd9\u4f1a\u5c06\u5b57\u7b26\u4e32\u503c\u8f6c\u6362\u4e3a TIMESTAMP \u503c\u3002<\/p>\n<h3>4.CAST()\u7684\u8bed\u6cd5\u53ca\u7528\u6cd5<\/h3>\n<p>\uff081\uff09\u8bed\u6cd5\uff1a<\/p>\n<pre><code>CAST(Expression AS Data_type)<\/code><\/pre>\n<p>\u5373CAST(\u8868\u8fbe\u5f0f AS \u6570\u636e\u7c7b\u578b)<br \/>\n\u53c2\u6570\u8bf4\u660e<\/p>\n<p>Expression \uff1a\u9700\u8981\u88ab\u8f6c\u6362\u7684\u8868\u8fbe\u5f0f\uff0c\u53ef\u4ee5\u662f\u5b57\u6bb5\u4e5f\u53ef\u4ee5\u662f\u5b57\u6bb5\u548c\u5176\u5b83\u51fd\u6570\u7ec4\u5408\u7684\u8868\u8fbe\u5f0f\u7b49\u3002<\/p>\n<p>AS \uff1a\u56fa\u5b9a\u7528\u6cd5\u683c\u5f0f\uff0c\u8fde\u63a5\u8868\u8fbe\u5f0f\u548c\u6570\u636e\u7c7b\u578b\uff0c\u201c\u8f6c\u4e3a\u201d\u7684\u610f\u601d\u3002<\/p>\n<p>Data_type \uff1a\u76ee\u6807\u6570\u636e\u7c7b\u578b\uff0c\u6570\u636e\u7c7b\u578b\u662fSQL\u81ea\u5e26\u7684\u4e0d\u80fd\u81ea\u5b9a\u4e49\uff0c\u4e3b\u8981\u6709CHAR,DATE,DATETIME,TIME,BINARY,DECIMAL,SIGNED,UNSIGNED\u7b49\u3002Decimal\u662f\u5177\u6709\u5c0f\u6570\u70b9\u800c\u4e14\u6570\u503c\u786e\u5b9a\u7684\u6570\u503c\u7c7b\u578b\u3002<\/p>\n<p>\uff082\uff09\u7528\u6cd5\uff1a\u5c06\u9700\u8981\u8f6c\u6362\u7684\u8868\u8fbe\u5f0f\u8f6c\u4e3a\u76ee\u6807\u7c7b\u578b\uff0c\u53ef\u4ee5\u662f\u83b7\u53d6\u76ee\u6807\u7c7b\u578b\u7684\u5b57\u6bb5\uff0c\u4e5f\u53ef\u4ee5\u4e0ewhere \u3001case when\u7b49\u8bed\u6cd5\u8fdb\u884c\u4f7f\u7528\u8fdb\u884c\u6bd4\u8f83\u7b49\u3002<br \/>\nCAST()\u7684\u7528\u6cd5\u4e0eExcel\u7684TEXT\u51fd\u6570\u7684\u7528\u6cd5\u975e\u5e38\u76f8\u4f3c\u3002<\/p>\n<h4>CAST()\u7684\u5b9e\u4f8b<\/h4>\n<p>\uff081\uff09\u5c06\u6587\u672c\uff08\u5b57\u7b26\u4e32\uff09\u65f6\u95f4\u8f6c\u4e3a\u65e5\u671f\u683c\u5f0f\uff0c\u83b7\u53d6\u65e5\u671f\u683c\u5f0f\u7684\u5b57\u6bb5<br \/>\n\u4f8b\uff1a\u4ece\u8868\u4e2d\u83b7\u53d6\u65e5\u671f\u683c\u5f0f\u7684\u65e5\u671f\u5b57\u6bb5\u3002\u5047\u8bbe\u8868\u540d\u4e3atable\uff0c\u50a8\u5b58\u65e5\u671f\u7684\u5b57\u6bb5\u662fctime\u3002<\/p>\n<pre><code>select substring_index(ctime,&#039; &#039;,1) as dt from table<\/code><\/pre>\n<p>\u83b7\u5f97\u7684\u7ed3\u679c\u4e3a\u5b57\u7b26\u4e32\uff08\u6587\u672c\uff09\u7c7b\u578b\u7684\u65f6\u95f4\uff0c\u9700\u8981\u83b7\u53d6\u65e5\u671f\u683c\u5f0f\u7684\u65e5\u671f\uff0c\u5219\u7528CAST()\u8f6c\u6362\u6210\u65e5\u671f\u683c\u5f0f\u3002\u201csubstring_index(ctime,' ',1)\u201d\u662f\u6307\u4ece\u5b57\u6bb5\u4e2d\u63d0\u53d6\u90e8\u5206\u503c\uff08\u76ee\u6807\u503c\uff09\u3002<\/p>\n<pre><code>select cast(substring_index(ctime,&#039; &#039;,1) as date) as dt from table<\/code><\/pre>\n<h3>\u603b\u7ed3\uff1a<\/h3>\n<p>\u56e0\u6b64\uff0c\u6709\u51e0\u79cd\u65b9\u6cd5\u53ef\u4ee5\u5728\u6570\u636e\u7c7b\u578b\u4e4b\u95f4\u8fdb\u884c\u8f6c\u6362\u3002CAST \u66f4\u901a\u7528\uff0c\u56e0\u4e3a\u5b83\u53ef\u4ee5\u5904\u7406\u66f4\u591a\u7684\u6570\u636e\u7c7b\u578b\uff0c\u4f46 TO_* \u51fd\u6570\u66f4\u5bb9\u6613\u4f7f\u7528\uff0c\u56e0\u4e3a\u5b83\u4eec\u7684\u53c2\u6570\u66f4\u5c11\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>1.\u5728 Oracle SQL \u4e2d\u8f6c\u6362\u4e3a\u6570\u5b57 \u53ef\u4ee5\u4f7f<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1816","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/www.821121.com\/index.php?rest_route=\/wp\/v2\/posts\/1816","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.821121.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.821121.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.821121.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.821121.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1816"}],"version-history":[{"count":1,"href":"http:\/\/www.821121.com\/index.php?rest_route=\/wp\/v2\/posts\/1816\/revisions"}],"predecessor-version":[{"id":1817,"href":"http:\/\/www.821121.com\/index.php?rest_route=\/wp\/v2\/posts\/1816\/revisions\/1817"}],"wp:attachment":[{"href":"http:\/\/www.821121.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1816"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.821121.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1816"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.821121.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1816"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}