{"id":108,"date":"2024-12-08T10:49:59","date_gmt":"2024-12-08T02:49:59","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=108"},"modified":"2024-12-08T10:49:59","modified_gmt":"2024-12-08T02:49:59","slug":"sql%e4%b8%ad%e7%9a%84sum%e5%87%bd%e6%95%b0%e7%9a%84%e7%94%a8%e6%b3%95","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2024\/12\/08\/sql%e4%b8%ad%e7%9a%84sum%e5%87%bd%e6%95%b0%e7%9a%84%e7%94%a8%e6%b3%95\/","title":{"rendered":"sql\u4e2d\u7684sum\u51fd\u6570\u7684\u7528\u6cd5"},"content":{"rendered":"\n
\n

\u5728 SQL \u4e2d\uff0cSUM<\/code> \u51fd\u6570\u7528\u4e8e\u8ba1\u7b97\u6570\u503c\u5217\u7684\u603b\u548c\u3002\u5b83\u5e38\u7528\u4e8e\u805a\u5408\u67e5\u8be2\u4e2d\uff0c\u5c24\u5176\u662f\u5728\u7ed3\u5408 GROUP BY<\/code> \u5b50\u53e5\u65f6\uff0c\u6765\u7edf\u8ba1\u5206\u7ec4\u7684\u603b\u548c\u3002\u4ee5\u4e0b\u662f SUM<\/code> \u51fd\u6570\u7684\u8be6\u7ec6\u7528\u6cd5\u548c\u793a\u4f8b\uff1a<\/p>\n<\/blockquote>\n\n\n\n

\n\n\n\n

\u57fa\u672c\u8bed\u6cd5<\/strong><\/h3>\n\n\n\n
SELECT SUM(column_name)\nFROM table_name\n[WHERE condition];<\/code><\/pre>\n\n\n\n
\n\n\n\n
\u7528\u6cd5\u793a\u4f8b<\/strong><\/h3>\n\n\n\n
1. \u8ba1\u7b97\u4e00\u5217\u7684\u603b\u548c<\/strong><\/h4>\n\n\n\n
SELECT SUM(salary) AS total_salary\nFROM employees;<\/code><\/pre>\n\n\n\n
\u8fd9\u6bb5\u4ee3\u7801\u4f1a\u8fd4\u56de employees<\/code> \u8868\u4e2d\u6240\u6709\u5458\u5de5\u7684 salary<\/code> \u603b\u548c\u3002<\/p>\n\n\n\n
\n\n\n\n
2. \u914d\u5408 WHERE<\/code> \u5b50\u53e5<\/strong><\/h4>\n\n\n\n
SELECT SUM(salary) AS total_salary\nFROM employees\nWHERE department_id = 101;<\/code><\/pre>\n\n\n\n
\u8fd9\u6bb5\u4ee3\u7801\u4f1a\u8fd4\u56de\u90e8\u95e8\u7f16\u53f7\u4e3a 101 \u7684\u6240\u6709\u5458\u5de5\u7684\u85aa\u8d44\u603b\u548c\u3002<\/p>\n\n\n\n
\n\n\n\n
3. \u914d\u5408 GROUP BY<\/code> \u5b50\u53e5<\/strong><\/h4>\n\n\n\n
SELECT department_id, SUM(salary) AS total_salary\nFROM employees\nGROUP BY department_id;<\/code><\/pre>\n\n\n\n
\u8fd9\u6bb5\u4ee3\u7801\u4f1a\u6309\u90e8\u95e8\u5206\u7ec4\uff0c\u8ba1\u7b97\u6bcf\u4e2a\u90e8\u95e8\u7684\u85aa\u8d44\u603b\u548c\u3002<\/p>\n\n\n\n
\n\n\n\n
4. \u5904\u7406\u91cd\u590d\u503c (DISTINCT<\/code>)<\/strong><\/h4>\n\n\n\n
\u5982\u679c\u5e0c\u671b\u53ea\u7edf\u8ba1\u67d0\u5217\u4e2d\u552f\u4e00\u503c\u7684\u603b\u548c\uff0c\u53ef\u4ee5\u4f7f\u7528 DISTINCT<\/code> \u5173\u952e\u5b57\uff1a<\/p>\n\n\n\n
SELECT SUM(DISTINCT salary) AS unique_salary_total\nFROM employees;<\/code><\/pre>\n\n\n\n
\u8fd9\u6bb5\u4ee3\u7801\u4f1a\u8ba1\u7b97 salary<\/code> \u5217\u4e2d\u552f\u4e00\u503c\u7684\u603b\u548c\u3002<\/p>\n\n\n\n
\n\n\n\n
5. \u914d\u5408\u5176\u4ed6\u805a\u5408\u51fd\u6570<\/strong><\/h4>\n\n\n\n
SUM<\/code> \u901a\u5e38\u4e0e\u5176\u4ed6\u805a\u5408\u51fd\u6570\u4e00\u8d77\u4f7f\u7528\uff0c\u4f8b\u5982 AVG<\/code>\u3001MAX<\/code>\u3001MIN<\/code> \u7b49\uff1a<\/p>\n\n\n\n
SELECT SUM(salary) AS total_salary, AVG(salary) AS avg_salary\nFROM employees;<\/code><\/pre>\n\n\n\n
\n\n\n\n
\u6ce8\u610f\u4e8b\u9879<\/strong><\/h3>\n\n\n\n
    \n
  1. \u975e\u6570\u503c\u5217<\/strong>\uff1a<\/li>\n<\/ol>\n\n\n\n
      \n
    • SUM<\/code> \u53ea\u80fd\u5bf9\u6570\u503c\u5217\u8fdb\u884c\u8ba1\u7b97\uff0c\u4f7f\u7528\u5728\u975e\u6570\u503c\u5217\u4e0a\u4f1a\u62a5\u9519\u3002<\/li>\n<\/ul>\n\n\n\n
        \n
      1. NULL<\/code> \u503c\u7684\u5904\u7406<\/strong>\uff1a<\/li>\n<\/ol>\n\n\n\n
          \n
        • SUM<\/code> \u4f1a\u81ea\u52a8\u5ffd\u7565\u5217\u4e2d\u7684 NULL<\/code> \u503c\u3002<\/li>\n\n\n\n
        • \u5982\u679c\u9700\u8981\u786e\u4fdd\u67d0\u5217\u4e0d\u4f1a\u56e0 NULL<\/code> \u503c\u5f71\u54cd\u7ed3\u679c\uff0c\u53ef\u4ee5\u4f7f\u7528 COALESCE<\/code> \u5c06 NULL<\/code> \u66ff\u6362\u4e3a 0\uff1a
          sql SELECT SUM(COALESCE(salary, 0)) AS total_salary FROM employees;<\/code><\/li>\n<\/ul>\n\n\n\n
            \n
          1. \u7ed3\u679c\u5217\u540d<\/strong>\uff1a<\/li>\n<\/ol>\n\n\n\n
              \n
            • \u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cSUM<\/code> \u8fd4\u56de\u7684\u5217\u540d\u53ef\u80fd\u662f\u51fd\u6570\u672c\u8eab\uff08\u5982 SUM(salary)<\/code>\uff09\uff0c\u53ef\u4ee5\u4f7f\u7528 AS<\/code> \u8bbe\u7f6e\u66f4\u53cb\u597d\u7684\u522b\u540d\u3002<\/li>\n<\/ul>\n\n\n\n
              \n\n\n\n
              \u7efc\u5408\u793a\u4f8b<\/strong><\/h3>\n\n\n\n
              \u5047\u8bbe\u6709\u4e00\u4e2a orders<\/code> \u8868\uff1a<\/p>\n\n\n\n
              order_id    customer_id    amount\n1           101            500\n2           102            300\n3           101            700\n4           103            NULL\n5           102            200<\/code><\/pre>\n\n\n\n
              \u793a\u4f8b\u67e5\u8be2<\/strong><\/h4>\n\n\n\n
                \n
              • \u8ba1\u7b97\u603b\u8ba2\u5355\u91d1\u989d<\/strong>\uff1a<\/li>\n<\/ul>\n\n\n\n
                  SELECT SUM(amount) AS total_amount\n  FROM orders;<\/code><\/pre>\n\n\n\n
                \u7ed3\u679c\uff1a1500<\/code><\/p>\n\n\n\n
                  \n
                • \u6309\u5ba2\u6237\u5206\u7ec4\u8ba1\u7b97\u8ba2\u5355\u91d1\u989d<\/strong>\uff1a<\/li>\n<\/ul>\n\n\n\n
                    SELECT customer_id, SUM(amount) AS total_amount\n  FROM orders\n  GROUP BY customer_id;<\/code><\/pre>\n\n\n\n
                  \u7ed3\u679c\uff1a<\/p>\n\n\n\n
                    customer_id    total_amount\n  101            1200\n  102            500\n  103            0<\/code><\/pre>\n\n\n\n
                  \u5982\u679c\u6709\u66f4\u591a\u7684\u5e94\u7528\u573a\u666f\u6216\u95ee\u9898\uff0c\u53ef\u4ee5\u968f\u65f6\u544a\u8bc9\u6211\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
                  \u5728 SQL \u4e2d\uff0cSUM \u51fd\u6570\u7528\u4e8e\u8ba1\u7b97\u6570\u503c\u5217\u7684\u603b\u548c\u3002\u5b83\u5e38\u7528\u4e8e\u805a\u5408\u67e5\u8be2\u4e2d\uff0c\u5c24\u5176\u662f\u5728\u7ed3\u5408 GROUP BY \u5b50\u53e5\u65f6\uff0c […]<\/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":[41,42,40],"class_list":["post-108","post","type-post","status-publish","format-standard","hentry","category-sql","tag-41","tag-42","tag-40"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/108","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=108"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/108\/revisions"}],"predecessor-version":[{"id":109,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/108\/revisions\/109"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=108"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=108"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=108"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}