{"id":60425,"date":"2024-10-13T02:45:15","date_gmt":"2024-10-12T18:45:15","guid":{"rendered":"https:\/\/server.hk\/cnblog\/60425\/"},"modified":"2024-10-13T02:45:15","modified_gmt":"2024-10-12T18:45:15","slug":"db2%e5%b8%b8%e7%94%a8%e5%87%bd%e6%95%b8%e7%9a%84%e7%a8%ae%e9%a1%9e%e8%88%87%e6%ad%a3%e7%a2%ba%e6%87%89%e7%94%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/60425\/","title":{"rendered":"DB2\u5e38\u7528\u51fd\u6578\u7684\u7a2e\u985e\u8207\u6b63\u78ba\u61c9\u7528"},"content":{"rendered":"<h1 id=\"db2%e5%b8%b8%e7%94%a8%e5%87%bd%e6%95%b8%e7%9a%84%e7%a8%ae%e9%a1%9e%e8%88%87%e6%ad%a3%e7%a2%ba%e6%87%89%e7%94%a8-hKUDNGgBvf\">DB2\u5e38\u7528\u51fd\u6578\u7684\u7a2e\u985e\u8207\u6b63\u78ba\u61c9\u7528<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cIBM\u7684DB2\u662f\u4e00\u500b\u529f\u80fd\u5f37\u5927\u7684\u9078\u64c7\uff0c\u5ee3\u6cdb\u61c9\u7528\u65bc\u4f01\u696d\u7d1a\u61c9\u7528\u7a0b\u5f0f\u4e2d\u3002DB2\u63d0\u4f9b\u4e86\u591a\u7a2e\u5167\u5efa\u51fd\u6578\uff0c\u9019\u4e9b\u51fd\u6578\u53ef\u4ee5\u5e6b\u52a9\u7528\u6236\u9032\u884c\u6578\u64da\u8655\u7406\u3001\u5206\u6790\u548c\u5831\u544a\u3002\u672c\u6587\u5c07\u63a2\u8a0eDB2\u5e38\u7528\u51fd\u6578\u7684\u7a2e\u985e\u53ca\u5176\u6b63\u78ba\u61c9\u7528\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u6709\u6548\u5730\u5229\u7528\u9019\u4e9b\u5de5\u5177\u3002<\/p>\n<h2 id=\"1-%e6%95%b8%e5%ad%b8%e5%87%bd%e6%95%b8-hKUDNGgBvf\">1. \u6578\u5b78\u51fd\u6578<\/h2>\n<p>\u6578\u5b78\u51fd\u6578\u5728DB2\u4e2d\u7528\u65bc\u57f7\u884c\u5404\u7a2e\u6578\u5b78\u8a08\u7b97\u3002\u5e38\u898b\u7684\u6578\u5b78\u51fd\u6578\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><code>ABS(x)<\/code>\uff1a\u8fd4\u56dex\u7684\u7d55\u5c0d\u503c\u3002<\/li>\n<li><code>CEIL(x)<\/code>\uff1a\u8fd4\u56de\u5927\u65bc\u6216\u7b49\u65bcx\u7684\u6700\u5c0f\u6574\u6578\u3002<\/li>\n<li><code>FLOOR(x)<\/code>\uff1a\u8fd4\u56de\u5c0f\u65bc\u6216\u7b49\u65bcx\u7684\u6700\u5927\u6574\u6578\u3002<\/li>\n<li><code>ROUND(x, d)<\/code>\uff1a\u5c07x\u56db\u6368\u4e94\u5165\u5230d\u4f4d\u5c0f\u6578\u3002<\/li>\n<\/ul>\n<p>\u4f8b\u5982\uff0c\u82e5\u8981\u8a08\u7b97\u4e00\u500b\u6578\u5b57\u7684\u7d55\u5c0d\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0bSQL\u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT ABS(-10) AS AbsoluteValue FROM SYSIBM.SYSDUMMY1;<\/code><\/pre>\n<h2 id=\"2-%e5%ad%97%e4%b8%b2%e5%87%bd%e6%95%b8-hKUDNGgBvf\">2. \u5b57\u4e32\u51fd\u6578<\/h2>\n<p>\u5b57\u4e32\u51fd\u6578\u7528\u65bc\u8655\u7406\u548c\u64cd\u4f5c\u5b57\u4e32\u6578\u64da\u3002DB2\u63d0\u4f9b\u4e86\u591a\u7a2e\u5b57\u4e32\u51fd\u6578\uff0c\u4f8b\u5982\uff1a<\/p>\n<ul>\n<li><code>CONCAT(string1, string2)<\/code>\uff1a\u5c07\u5169\u500b\u5b57\u4e32\u9023\u63a5\u5728\u4e00\u8d77\u3002<\/li>\n<li><code>LENGTH(string)<\/code>\uff1a\u8fd4\u56de\u5b57\u4e32\u7684\u9577\u5ea6\u3002<\/li>\n<li><code>SUBSTR(string, start, length)<\/code>\uff1a\u8fd4\u56de\u5f9estart\u4f4d\u7f6e\u958b\u59cb\u7684\u6307\u5b9a\u9577\u5ea6\u7684\u5b50\u5b57\u4e32\u3002<\/li>\n<li><code>UPPER(string)<\/code>\uff1a\u5c07\u5b57\u4e32\u8f49\u63db\u70ba\u5927\u5beb\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528\u5b57\u4e32\u51fd\u6578\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>SELECT CONCAT('Hello', ' World') AS Greeting FROM SYSIBM.SYSDUMMY1;<\/code><\/pre>\n<h2 id=\"3-%e6%97%a5%e6%9c%9f%e5%92%8c%e6%99%82%e9%96%93%e5%87%bd%e6%95%b8-hKUDNGgBvf\">3. \u65e5\u671f\u548c\u6642\u9593\u51fd\u6578<\/h2>\n<p>\u65e5\u671f\u548c\u6642\u9593\u51fd\u6578\u5728\u8655\u7406\u6642\u9593\u6233\u548c\u65e5\u671f\u6642\u975e\u5e38\u6709\u7528\u3002\u5e38\u898b\u7684\u65e5\u671f\u548c\u6642\u9593\u51fd\u6578\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><code>CURRENT DATE<\/code>\uff1a\u8fd4\u56de\u7576\u524d\u65e5\u671f\u3002<\/li>\n<li><code>CURRENT TIME<\/code>\uff1a\u8fd4\u56de\u7576\u524d\u6642\u9593\u3002<\/li>\n<li><code>DATEPART(date, part)<\/code>\uff1a\u8fd4\u56de\u6307\u5b9a\u65e5\u671f\u90e8\u5206\uff08\u5982\u5e74\u3001\u6708\u3001\u65e5\uff09\u3002<\/li>\n<li><code>DATEDIFF(date1, date2)<\/code>\uff1a\u8a08\u7b97\u5169\u500b\u65e5\u671f\u4e4b\u9593\u7684\u5dee\u7570\u3002<\/li>\n<\/ul>\n<p>\u4f8b\u5982\uff0c\u82e5\u8981\u7372\u53d6\u7576\u524d\u65e5\u671f\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0bSQL\u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT CURRENT DATE AS Today FROM SYSIBM.SYSDUMMY1;<\/code><\/pre>\n<h2 id=\"4-%e8%81%9a%e5%90%88%e5%87%bd%e6%95%b8-hKUDNGgBvf\">4. \u805a\u5408\u51fd\u6578<\/h2>\n<p>\u805a\u5408\u51fd\u6578\u7528\u65bc\u5c0d\u4e00\u7d44\u503c\u9032\u884c\u8a08\u7b97\uff0c\u4e26\u8fd4\u56de\u55ae\u4e00\u503c\u3002\u5e38\u898b\u7684\u805a\u5408\u51fd\u6578\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><code>SUM(column)<\/code>\uff1a\u8a08\u7b97\u6307\u5b9a\u5217\u7684\u7e3d\u548c\u3002<\/li>\n<li><code>AVG(column)<\/code>\uff1a\u8a08\u7b97\u6307\u5b9a\u5217\u7684\u5e73\u5747\u503c\u3002<\/li>\n<li><code>COUNT(column)<\/code>\uff1a\u8a08\u7b97\u6307\u5b9a\u5217\u7684\u884c\u6578\u3002<\/li>\n<li><code>MAX(column)<\/code>\uff1a\u8fd4\u56de\u6307\u5b9a\u5217\u7684\u6700\u5927\u503c\u3002<\/li>\n<li><code>MIN(column)<\/code>\uff1a\u8fd4\u56de\u6307\u5b9a\u5217\u7684\u6700\u5c0f\u503c\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528\u805a\u5408\u51fd\u6578\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>SELECT COUNT(*) AS TotalRecords FROM Employees;<\/code><\/pre>\n<h2 id=\"5-%e6%a2%9d%e4%bb%b6%e5%87%bd%e6%95%b8-hKUDNGgBvf\">5. \u689d\u4ef6\u51fd\u6578<\/h2>\n<p>\u689d\u4ef6\u51fd\u6578\u7528\u65bc\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u503c\u3002\u6700\u5e38\u7528\u7684\u689d\u4ef6\u51fd\u6578\u662f\uff1a<\/p>\n<ul>\n<li><code>CASE<\/code>\uff1a\u6839\u64da\u689d\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u7d50\u679c\u3002<\/li>\n<li><code>COALESCE(value1, value2, ...)<\/code>\uff1a\u8fd4\u56de\u7b2c\u4e00\u500b\u975e\u7a7a\u503c\u3002<\/li>\n<\/ul>\n<p>\u4f8b\u5982\uff0c\u4f7f\u7528CASE\u51fd\u6578\u4f86\u6839\u64da\u5206\u6578\u8a55\u5206\uff1a<\/p>\n<pre><code>SELECT \n    CASE \n        WHEN score &gt;= 90 THEN 'A'\n        WHEN score &gt;= 80 THEN 'B'\n        WHEN score &gt;= 70 THEN 'C'\n        ELSE 'D'\n    END AS Grade\nFROM Students;<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-hKUDNGgBvf\">\u7e3d\u7d50<\/h2>\n<p>DB2\u63d0\u4f9b\u4e86\u591a\u7a2e\u51fd\u6578\uff0c\u5e6b\u52a9\u7528\u6236\u5728\u6578\u64da\u8655\u7406\u548c\u5206\u6790\u4e2d\u63d0\u9ad8\u6548\u7387\u3002\u4e86\u89e3\u9019\u4e9b\u51fd\u6578\u7684\u7a2e\u985e\u53ca\u5176\u6b63\u78ba\u61c9\u7528\uff0c\u5c0d\u65bc\u958b\u767c\u8005\u4f86\u8aaa\u81f3\u95dc\u91cd\u8981\u3002\u7121\u8ad6\u662f\u6578\u5b78\u8a08\u7b97\u3001\u5b57\u4e32\u8655\u7406\u3001\u65e5\u671f\u6642\u9593\u64cd\u4f5c\u3001\u805a\u5408\u8a08\u7b97\u9084\u662f\u689d\u4ef6\u5224\u65b7\uff0cDB2\u7684\u51fd\u6578\u90fd\u80fd\u63d0\u4f9b\u5f37\u5927\u7684\u652f\u6301\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u4f01\u696d\uff0c\u9078\u64c7\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4e5f\u662f\u4e00\u500b\u91cd\u8981\u8003\u91cf\uff0c\u9019\u6a23\u53ef\u4ee5\u78ba\u4fdd\u6578\u64da\u5eab\u7684\u7a69\u5b9a\u6027\u548c\u6027\u80fd\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22DB2\u5e38\u7528\u51fd\u6578\u7684\u7a2e\u985e\u53ca\u5176\u6b63\u78ba\u61c9\u7528\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\uff0c\u512a\u5316\u67e5\u8a62\u6027\u80fd\uff0c\u52a9\u529b\u6578\u64da\u7ba1\u7406\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-60425","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60425","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=60425"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60425\/revisions"}],"predecessor-version":[{"id":60426,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60425\/revisions\/60426"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=60425"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=60425"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=60425"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}