{"id":5218,"date":"2024-11-14T12:14:24","date_gmt":"2024-11-14T04:14:24","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5218\/"},"modified":"2024-11-14T12:14:24","modified_gmt":"2024-11-14T04:14:24","slug":"oracle-cast%e5%87%bd%e6%95%b0%e7%94%a8%e6%b3%95","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5218\/","title":{"rendered":"oracle cast\u51fd\u6570\u7528\u6cd5"},"content":{"rendered":"

\n oracle \u4e2d\u7684 cast \u51fd\u6570\u7528\u4e8e\u5c06\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u8f6c\u6362\u4e3a\u53e6\u4e00\u79cd\u6570\u636e\u7c7b\u578b\uff0c\u652f\u6301\u5404\u79cd\u6570\u636e\u7c7b\u578b\u8f6c\u6362\uff0c\u5305\u62ec\u6570\u503c\u3001\u5b57\u7b26\u3001\u65e5\u671f\u548c\u5e03\u5c14\u7c7b\u578b\uff0c\u4ee5\u53ca\u81ea\u5b9a\u4e49\u7c7b\u578b\u3002\u7279\u5b9a\u8bed\u6cd5\u4e3a\uff1acast(expression as data_type)\uff0c\u5176\u4e2d expression \u4e3a\u8981\u8f6c\u6362\u7684\u8868\u8fbe\u5f0f\uff0cdata_type \u4e3a\u8981\u8f6c\u6362\u5230\u7684\u6570\u636e\u7c7b\u578b\u3002\n<\/p><\/blockquote>\n

\"oracle<\/p>\n

Oracle CAST \u51fd\u6570\u7528\u6cd5<\/strong><\/p>\n

\u4ec0\u4e48\u662f CAST \u51fd\u6570\uff1f<\/strong><\/p>\n

CAST \u51fd\u6570\u5728 Oracle \u4e2d\u7528\u4e8e\u5c06\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u8f6c\u6362\u4e3a\u53e6\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u3002<\/p>\n

\u8bed\u6cd5\uff1a<\/strong><\/p>\n

CAST(expression AS data_type)<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
\u5176\u4e2d\uff1a<\/p>\n
    \n
  • expression\uff1a\u8981\u8f6c\u6362\u7684\u8868\u8fbe\u5f0f<\/li>\n
  • data_type\uff1a\u8981\u8f6c\u6362\u5230\u7684\u6570\u636e\u7c7b\u578b<\/li>\n<\/ul>\n
    \u6570\u636e\u7c7b\u578b\u8f6c\u6362\u89c4\u5219\uff1a<\/strong><\/p>\n
    CAST \u51fd\u6570\u652f\u6301\u5404\u79cd\u6570\u636e\u7c7b\u578b\u4e4b\u95f4\u7684\u8f6c\u6362\uff0c\u5305\u62ec\uff1a<\/p>\n
      \n
    • \u6570\u503c\u7c7b\u578b\uff08NUMBER\u3001INTEGER\u3001FLOAT\uff09<\/li>\n
    • \u5b57\u7b26\u7c7b\u578b\uff08VARCHAR2\u3001CHAR\uff09<\/li>\n
    • \u65e5\u671f\u7c7b\u578b\uff08DATE\u3001TIMESTAMP\uff09<\/li>\n
    • \u5e03\u5c14\u7c7b\u578b\uff08BOOLEAN\uff09<\/li>\n
    • \u81ea\u5b9a\u4e49\u7c7b\u578b<\/li>\n<\/ul>\n
      \u793a\u4f8b\uff1a<\/strong><\/p>\n
        \n
      • \u5c06\u6570\u5b57 123 \u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff1a<\/li>\n<\/ul>\n
        SELECT CAST(123 AS VARCHAR2(10)) FROM dual;<\/pre>\n
         \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
          \n
        • \u5c06\u65e5\u671f ‘2023-03-08’ \u8f6c\u6362\u4e3a\u6570\u5b57\uff1a<\/li>\n<\/ul>\n
          SELECT CAST('2023-03-08' AS NUMBER) FROM dual;<\/pre>\n
           \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
            \n
          • \u5c06\u5e03\u5c14\u503c TRUE \u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff1a<\/li>\n<\/ul>\n
            SELECT CAST(TRUE AS VARCHAR2(10)) FROM dual;<\/pre>\n
             \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
              \n
            • \u5c06\u81ea\u5b9a\u4e49\u7c7b\u578b Employee \u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff1a<\/li>\n<\/ul>\n
              SELECT CAST(e AS VARCHAR2(200)) FROM employee e;<\/pre>\n
               \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
              \u6ce8\u610f\u4e8b\u9879\uff1a<\/strong><\/p>\n
                \n
              • \u8f6c\u6362\u53ef\u80fd\u5bfc\u81f4\u6570\u636e\u7cbe\u5ea6\u635f\u5931\u6216\u622a\u65ad\u3002<\/li>\n
              • \u786e\u4fdd\u8981\u8f6c\u6362\u7684\u503c\u4e0e\u76ee\u6807\u6570\u636e\u7c7b\u578b\u517c\u5bb9\u3002<\/li>\n
              • CAST \u51fd\u6570\u4e0d\u80fd\u7528\u4e8e\u8f6c\u6362 NULL \u503c\u3002<\/li>\n
              • \u53ef\u4ee5\u5728 SQL \u67e5\u8be2\u3001PL\/SQL \u5757\u548c\u5b58\u50a8\u8fc7\u7a0b\u4e2d\u4f7f\u7528 CAST \u51fd\u6570\u3002<\/li>\n<\/ul>\n
                \u4ee5\u4e0a\u5c31\u662f cast\u51fd\u6570\u7528\u6cd5\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":"
                oracle \u4e2d\u7684 cast \u51fd\u6570\u7528\u4e8e\u5c06\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u8f6c\u6362\u4e3a\u53e6\u4e00\u79cd\u6570\u636e\u7c7b\u578b\uff0c\u652f\u6301\u5404\u79cd\u6570\u636e\u7c7b\u578b\u8f6c\u6362\uff0c\u5305\u62ec\u6570\u503c\u3001\u5b57\u7b26\u3001\u65e5\u671f\u548c\u5e03\u5c14\u7c7b\u578b\uff0c\u4ee5\u53ca\u81ea\u5b9a\u4e49\u7c7b\u578b\u3002\u7279\u5b9a\u8bed\u6cd5\u4e3a\uff1acast(expression as data_type)\uff0c\u5176\u4e2d expression \u4e3a\u8981\u8f6c\u6362\u7684\u8868\u8fbe\u5f0f\uff0cdata_type \u4e3a\u8981\u8f6c\u6362\u5230\u7684\u6570\u636e\u7c7b\u578b\u3002 Oracle CAST \u51fd\u6570\u7528\u6cd5 \u4ec0\u4e48\u662f CAST \u51fd\u6570\uff1f CAST \u51fd\u6570\u5728 Oracle \u4e2d\u7528\u4e8e\u5c06\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u8f6c\u6362\u4e3a\u53e6\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u3002 \u8bed\u6cd5\uff1a CAST(expression AS data_type) \u767b\u5f55\u540e\u590d\u5236 \u5176\u4e2d\uff1a expression\uff1a\u8981\u8f6c\u6362\u7684\u8868\u8fbe\u5f0f data_type\uff1a\u8981\u8f6c\u6362\u5230\u7684\u6570\u636e\u7c7b\u578b \u6570\u636e\u7c7b\u578b\u8f6c\u6362\u89c4\u5219\uff1a CAST \u51fd\u6570\u652f\u6301\u5404\u79cd\u6570\u636e\u7c7b\u578b\u4e4b\u95f4\u7684\u8f6c\u6362\uff0c\u5305\u62ec\uff1a \u6570\u503c\u7c7b\u578b\uff08NUMBER\u3001INTEGER\u3001FLOAT\uff09 \u5b57\u7b26\u7c7b\u578b\uff08VARCHAR2\u3001CHAR\uff09 \u65e5\u671f\u7c7b\u578b\uff08DATE\u3001TIMESTAMP\uff09 \u5e03\u5c14\u7c7b\u578b\uff08BOOLEAN\uff09 \u81ea\u5b9a\u4e49\u7c7b\u578b \u793a\u4f8b\uff1a \u5c06\u6570\u5b57 123 \u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff1a SELECT CAST(123 AS VARCHAR2(10)) FROM dual; \u767b\u5f55\u540e\u590d\u5236 \u5c06\u65e5\u671f ‘2023-03-08’ \u8f6c\u6362\u4e3a\u6570\u5b57\uff1a SELECT CAST(‘2023-03-08’ AS NUMBER) FROM dual; […]<\/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-5218","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5218","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=5218"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5218\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5218"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5218"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}