{"id":110,"date":"2024-12-08T10:58:54","date_gmt":"2024-12-08T02:58:54","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=110"},"modified":"2024-12-08T10:58:54","modified_gmt":"2024-12-08T02:58:54","slug":"sql%e4%b8%ad%e7%9a%84sum%e6%98%af%e6%80%8e%e4%b9%88%e8%bf%90%e7%ae%97%e7%9a%84","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2024\/12\/08\/sql%e4%b8%ad%e7%9a%84sum%e6%98%af%e6%80%8e%e4%b9%88%e8%bf%90%e7%ae%97%e7%9a%84\/","title":{"rendered":"sql\u4e2d\u7684sum\u662f\u600e\u4e48\u8fd0\u7b97\u7684"},"content":{"rendered":"\n
\n

\u5728 SQL \u4e2d\uff0cSUM<\/code> \u7528\u4e8e\u8ba1\u7b97\u4e00\u7ec4\u6570\u5b57\u7684\u603b\u548c\u7684\u805a\u5408\u51fd\u6570\uff0c\u901a\u8fc7\u9010\u884c\u7d2f\u52a0\u7684\u65b9\u5f0f\u8ba1\u7b97\u4e00\u4e2a\u6570\u503c\u5217\u7684\u603b\u548c\uff0c\u5ffd\u7565\u5176\u4e2d\u7684 NULL<\/code> \u503c\u3002\u4ee5\u4e0b\u662f\u5b83\u7684\u5de5\u4f5c\u539f\u7406\u548c\u8ba1\u7b97\u7ec6\u8282\uff1a<\/p>\n<\/blockquote>\n\n\n\n

\n\n\n\n

\u8fd0\u7b97\u539f\u7406<\/strong><\/h3>\n\n\n\n
    \n
  1. \u9010\u884c\u7d2f\u52a0<\/strong>
    SQL \u5f15\u64ce\u4f1a\u4ece\u76ee\u6807\u8868\u4e2d\u9010\u884c\u8bfb\u53d6\u6307\u5b9a\u5217\u7684\u503c\uff0c\u5e76\u5c06\u8fd9\u4e9b\u503c\u76f8\u52a0\uff0c\u6700\u7ec8\u8fd4\u56de\u7ed3\u679c\u3002<\/li>\n\n\n\n
  2. \u5ffd\u7565 NULL<\/code> \u503c<\/strong>
    \u5982\u679c\u5217\u4e2d\u7684\u67d0\u4e9b\u884c\u503c\u662f NULL<\/code>\uff0cSUM<\/code> \u4f1a\u8df3\u8fc7\u8fd9\u4e9b\u503c\uff0c\u800c\u4e0d\u4f1a\u5c06\u5b83\u4eec\u89c6\u4e3a 0\u3002<\/li>\n\n\n\n
  3. \u57fa\u4e8e\u8fc7\u6ee4\u6761\u4ef6<\/strong>
    \u5982\u679c\u4f7f\u7528\u4e86 WHERE<\/code> \u6216\u5176\u4ed6\u8fc7\u6ee4\u6761\u4ef6\uff0cSUM<\/code> \u53ea\u4f1a\u5bf9\u6ee1\u8db3\u6761\u4ef6\u7684\u884c\u8fdb\u884c\u7d2f\u52a0\u3002<\/li>\n\n\n\n
  4. \u5206\u7ec4\u8fd0\u7b97<\/strong>
    \u5f53\u7ed3\u5408 GROUP BY<\/code> \u4f7f\u7528\u65f6\uff0cSUM<\/code> \u4f1a\u6309\u7167\u5206\u7ec4\u6761\u4ef6\u5bf9\u6bcf\u7ec4\u7684\u6570\u636e\u5206\u522b\u8ba1\u7b97\u603b\u548c\u3002<\/li>\n<\/ol>\n\n\n\n
    \n\n\n\n

    \u8fd0\u7b97\u8fc7\u7a0b\u793a\u4f8b<\/strong><\/h3>\n\n\n\n

    \u5047\u8bbe\u6709\u4e00\u4e2a\u540d\u4e3a sales<\/code> \u7684\u8868\uff1a<\/p>\n\n\n\n

    ID<\/th>Product<\/th>Sales<\/th><\/tr><\/thead>
    1<\/td>A<\/td>100<\/td><\/tr>
    2<\/td>B<\/td>200<\/td><\/tr>
    3<\/td>C<\/td>NULL<\/td><\/tr>
    4<\/td>A<\/td>150<\/td><\/tr>
    5<\/td>B<\/td>250<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    \u603b\u548c\u8ba1\u7b97<\/strong><\/h4>\n\n\n\n
    SELECT SUM(Sales) AS TotalSales\nFROM sales;<\/code><\/pre>\n\n\n\n
    \u8fd0\u7b97\u8fc7\u7a0b\uff1a<\/strong><\/p>\n\n\n\n
      \n
    1. \u904d\u5386 Sales<\/code> \u5217\uff0c\u5206\u522b\u8bfb\u53d6\u503c\uff1a100, 200, NULL, 150, 250<\/code>\u3002<\/li>\n\n\n\n
    2. \u5ffd\u7565 NULL<\/code> \u503c\u3002<\/li>\n\n\n\n
    3. \u5c06\u5176\u4f59\u6570\u503c\u7d2f\u52a0\uff1a100 + 200 + 150 + 250 = 700<\/code>\u3002<\/li>\n<\/ol>\n\n\n\n
      \u7ed3\u679c\uff1a<\/strong> 700<\/code><\/p>\n\n\n\n
      \n\n\n\n
      \u5206\u7ec4\u8ba1\u7b97<\/strong><\/h4>\n\n\n\n
      SELECT Product, SUM(Sales) AS TotalSales\nFROM sales\nGROUP BY Product;<\/code><\/pre>\n\n\n\n
      \u8fd0\u7b97\u8fc7\u7a0b\uff1a<\/strong><\/p>\n\n\n\n
        \n
      1. \u6839\u636e Product<\/code> \u5217\u5206\u7ec4\uff1aA, B, C<\/code>\u3002<\/li>\n\n\n\n
      2. \u5bf9\u6bcf\u7ec4\u7684 Sales<\/code> \u5217\u8fdb\u884c\u7d2f\u52a0\uff1a<\/li>\n<\/ol>\n\n\n\n
          \n
        • \u7ec4 A:<\/strong> 100 + 150 = 250<\/code><\/li>\n\n\n\n
        • \u7ec4 B:<\/strong> 200 + 250 = 450<\/code><\/li>\n\n\n\n
        • \u7ec4 C:<\/strong> \u8df3\u8fc7 NULL<\/code>\uff0c\u603b\u548c\u4e3a 0<\/code>\uff08\u7ed3\u679c\u4e2d\u53ef\u80fd\u4f1a\u663e\u793a\u4e3a NULL<\/code>\uff0c\u5177\u4f53\u4f9d\u6570\u636e\u5e93\u800c\u5b9a\uff09\u3002<\/li>\n<\/ul>\n\n\n\n
            \n
          1. \u8fd4\u56de\u7ed3\u679c\u3002<\/li>\n<\/ol>\n\n\n\n
            \u7ed3\u679c\uff1a<\/strong><\/p>\n\n\n\n
            Product<\/th>TotalSales<\/th><\/tr><\/thead>
            A<\/td>250<\/td><\/tr>
            B<\/td>450<\/td><\/tr>
            C<\/td>NULL \u6216 0<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
            \n\n\n\n
            \u7279\u6b8a\u60c5\u51b5\u5904\u7406<\/strong><\/h3>\n\n\n\n
            1. NULL<\/code> \u503c\u5f71\u54cd<\/strong><\/h4>\n\n\n\n
            \u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cSUM<\/code> \u4f1a\u5ffd\u7565 NULL<\/code>\u3002\u5982\u679c\u5e0c\u671b\u5f3a\u5236\u5c06 NULL<\/code> \u89c6\u4e3a 0\uff0c\u53ef\u4ee5\u4f7f\u7528 COALESCE<\/code> \u51fd\u6570\uff1a<\/p>\n\n\n\n
            SELECT SUM(COALESCE(Sales, 0)) AS TotalSales\nFROM sales;<\/code><\/pre>\n\n\n\n
            2. \u91cd\u590d\u503c\u7684\u603b\u548c<\/strong><\/h4>\n\n\n\n
            \u5982\u679c\u9700\u8981\u53ea\u8ba1\u7b97\u552f\u4e00\u503c\u7684\u603b\u548c\uff0c\u53ef\u4ee5\u4f7f\u7528 DISTINCT<\/code>\uff1a<\/p>\n\n\n\n
            SELECT SUM(DISTINCT Sales) AS TotalSales\nFROM sales;<\/code><\/pre>\n\n\n\n
            \u8ba1\u7b97\u8fc7\u7a0b\uff1a<\/strong><\/p>\n\n\n\n
              \n
            • \u63d0\u53d6\u552f\u4e00\u503c\uff1a100, 200, 150, 250<\/code>\u3002<\/li>\n\n\n\n
            • \u603b\u548c\uff1a100 + 200 + 150 + 250 = 700<\/code>\u3002<\/li>\n<\/ul>\n\n\n\n
              3. \u7ed3\u5408\u8fc7\u6ee4\u6761\u4ef6<\/strong><\/h4>\n\n\n\n
              \u4f7f\u7528 WHERE<\/code> \u5b50\u53e5\u8fc7\u6ee4\u6570\u636e\uff0cSUM<\/code> \u4ec5\u4f5c\u7528\u4e8e\u7b26\u5408\u6761\u4ef6\u7684\u884c\uff1a<\/p>\n\n\n\n
              SELECT SUM(Sales) AS TotalSales\nFROM sales\nWHERE Product = 'A';<\/code><\/pre>\n\n\n\n
              \u7ed3\u679c\uff1a<\/strong> \u8ba1\u7b97 Product = 'A'<\/code> \u7684\u884c\uff0c\u603b\u548c\u4e3a\uff1a100 + 150 = 250<\/code>\u3002<\/p>\n\n\n\n
              \n\n\n\n
              \u603b\u7ed3<\/strong><\/h3>\n\n\n\n
                \n
              • SUM<\/code> \u4f1a\u5bf9\u6570\u503c\u5217\u4e2d\u7684\u6bcf\u4e00\u884c\u7d2f\u52a0\uff0c\u4f46\u8df3\u8fc7 NULL<\/code> \u503c\u3002<\/li>\n\n\n\n
              • \u53ef\u4ee5\u901a\u8fc7 GROUP BY<\/code> \u5b9e\u73b0\u5206\u7ec4\u603b\u548c\u8ba1\u7b97\u3002<\/li>\n\n\n\n
              • \u4f7f\u7528 COALESCE<\/code> \u6216 ISNULL<\/code> \u7b49\u51fd\u6570\uff0c\u53ef\u4ee5\u66f4\u7075\u6d3b\u5730\u5904\u7406 NULL<\/code> \u503c\u3002<\/li>\n\n\n\n
              • \u4e0e\u5176\u4ed6\u805a\u5408\u51fd\u6570\uff08\u5982 AVG<\/code>\u3001MAX<\/code> \u7b49\uff09\u4e00\u8d77\u4f7f\u7528\uff0c\u80fd\u6ee1\u8db3\u590d\u6742\u7684\u7edf\u8ba1\u9700\u6c42\u3002<\/li>\n\n\n\n
              • <\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
                \u5728 SQL \u4e2d\uff0cSUM \u7528\u4e8e\u8ba1\u7b97\u4e00\u7ec4\u6570\u5b57\u7684\u603b\u548c\u7684\u805a\u5408\u51fd\u6570\uff0c\u901a\u8fc7\u9010\u884c\u7d2f\u52a0\u7684\u65b9\u5f0f\u8ba1\u7b97\u4e00\u4e2a\u6570\u503c\u5217\u7684\u603b\u548c\uff0c\u5ffd\u7565\u5176\u4e2d\u7684  […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[36],"tags":[43],"class_list":["post-110","post","type-post","status-publish","format-standard","hentry","category-sql","tag-43"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/110","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=110"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/110\/revisions"}],"predecessor-version":[{"id":111,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/110\/revisions\/111"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=110"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=110"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=110"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}