{"id":1721,"date":"2025-02-16T08:53:31","date_gmt":"2025-02-16T00:53:31","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=1721"},"modified":"2025-02-16T08:53:31","modified_gmt":"2025-02-16T00:53:31","slug":"sql-max-%e5%87%bd%e6%95%b0","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/02\/16\/sql-max-%e5%87%bd%e6%95%b0\/","title":{"rendered":"SQL MAX() \u51fd\u6570"},"content":{"rendered":"\n

MAX()<\/code> \u51fd\u6570\u662f\u4e00\u4e2a\u805a\u5408\u51fd\u6570\uff0c\u7528\u4e8e\u8fd4\u56de\u6307\u5b9a\u5217\u4e2d\u7684\u6700\u5927\u503c<\/strong>\u3002\u5b83\u5e7f\u6cdb\u5e94\u7528\u4e8e SQL \u67e5\u8be2\u4e2d\uff0c\u5c24\u5176\u662f\u7528\u4e8e\u67e5\u627e\u6570\u636e\u96c6\u4e2d\u7684\u6700\u5927\u503c\uff0c\u6bd4\u5982\u627e\u51fa\u8868\u4e2d\u7684\u6700\u9ad8\u85aa\u6c34\u3001\u6700\u9ad8\u6210\u7ee9\u7b49\u3002<\/p>\n\n\n\n

1. MAX()<\/code> \u51fd\u6570\u6982\u8ff0<\/strong><\/h3>\n\n\n\n
    \n
  • \u4f5c\u7528<\/strong>\uff1aMAX()<\/code> \u51fd\u6570\u8fd4\u56de\u67d0\u5217\u7684\u6700\u5927\u503c\u3002\u53ef\u4ee5\u7528\u4e8e\u6570\u503c\u3001\u65e5\u671f\u548c\u5b57\u7b26\u6570\u636e\u7c7b\u578b\u3002<\/li>\n\n\n\n
  • \u8bed\u6cd5<\/strong>\uff1a<\/li>\n<\/ul>\n\n\n\n
      SELECT MAX(column_name)\n  FROM table_name\n  WHERE condition;<\/code><\/pre>\n\n\n\n
      \n
    • column_name<\/code>\uff1a\u8981\u67e5\u627e\u6700\u5927\u503c\u7684\u5217\u3002<\/li>\n\n\n\n
    • table_name<\/code>\uff1a\u67e5\u8be2\u7684\u8868\u540d\u3002<\/li>\n\n\n\n
    • condition<\/code>\uff1a\u53ef\u9009\u7684\u7b5b\u9009\u6761\u4ef6\uff0c\u7528\u4e8e\u6307\u5b9a\u54ea\u4e9b\u884c\u8981\u8003\u8651\u3002<\/li>\n<\/ul>\n\n\n\n
      2. MAX()<\/code> \u51fd\u6570\u7684\u5e94\u7528<\/strong><\/h3>\n\n\n\n
      MAX()<\/code> \u51fd\u6570\u53ef\u4ee5\u5e94\u7528\u4e8e\u6570\u503c\u3001\u65e5\u671f\u548c\u5b57\u7b26\u5217\u3002\u4e0b\u9762\u662f\u4e00\u4e9b\u5e38\u89c1\u7684\u4f8b\u5b50\u3002<\/p>\n\n\n\n
      2.1 \u6570\u503c\u5217\u7684\u4f7f\u7528<\/strong><\/h4>\n\n\n\n
      \u5047\u8bbe\u4f60\u6709\u4e00\u4e2a\u540d\u4e3a employees<\/code> \u7684\u8868\uff0c\u5305\u542b\u4ee5\u4e0b\u6570\u636e\uff1a<\/p>\n\n\n\n
      employee_id<\/th>name<\/th>salary<\/th><\/tr><\/thead>
      1<\/td>Tom<\/td>5000<\/td><\/tr>
      2<\/td>Jane<\/td>6000<\/td><\/tr>
      3<\/td>Bob<\/td>7000<\/td><\/tr>
      4<\/td>Alice<\/td>8000<\/td><\/tr>
      5<\/td>Mike<\/td>5500<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \u67e5\u8be2\u8868\u4e2d\u7684\u6700\u5927\u85aa\u6c34\uff1a<\/p>\n\n\n\n
      SELECT MAX(salary) AS max_salary\nFROM employees;<\/code><\/pre>\n\n\n\n
      \u7ed3\u679c<\/strong>\uff1a<\/p>\n\n\n\n
      max_salary<\/th><\/tr><\/thead>
      8000<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      2.2 \u65e5\u671f\u5217\u7684\u4f7f\u7528<\/strong><\/h4>\n\n\n\n
      \u5982\u679c\u4f60\u60f3\u627e\u5230\u516c\u53f8\u4e2d\u96c7\u4f63\u7684\u6700\u540e\u4e00\u4f4d\u5458\u5de5\u7684\u5165\u804c\u65e5\u671f\uff0c\u53ef\u4ee5\u67e5\u8be2\u65e5\u671f\u5217\u7684\u6700\u5927\u503c\uff1a<\/p>\n\n\n\n
      SELECT MAX(hire_date) AS latest_hire_date\nFROM employees;<\/code><\/pre>\n\n\n\n
      2.3 \u5b57\u7b26\u5217\u7684\u4f7f\u7528<\/strong><\/h4>\n\n\n\n
      \u4f60\u8fd8\u53ef\u4ee5\u4f7f\u7528 MAX()<\/code> \u6765\u67e5\u627e\u5b57\u7b26\u4e32\u5217\u4e2d\u7684\u6700\u5927\u503c\uff0c\u901a\u5e38\u662f\u5b57\u5178\u987a\u5e8f\u4e2d\u7684\u6700\u5927\u503c\u3002\u4f8b\u5982\uff0c\u67e5\u8be2\u8868\u4e2d\u59d3\u540d\u6309\u5b57\u6bcd\u987a\u5e8f\u6392\u5217\u7684\u6700\u5927\u503c\uff1a<\/p>\n\n\n\n
      SELECT MAX(name) AS last_name\nFROM employees;<\/code><\/pre>\n\n\n\n
      \u8fd9\u4f1a\u8fd4\u56de\u6309\u5b57\u6bcd\u987a\u5e8f\u6392\u5217\u7684\u6700\u5927\u540d\u5b57\u3002<\/p>\n\n\n\n
      3. \u4e0e GROUP BY<\/code> \u5b50\u53e5\u4e00\u8d77\u4f7f\u7528<\/strong><\/h3>\n\n\n\n
      MAX()<\/code> \u51fd\u6570\u7ecf\u5e38\u4e0e GROUP BY<\/code> \u5b50\u53e5\u4e00\u8d77\u4f7f\u7528\uff0c\u4ee5\u4fbf\u8ba1\u7b97\u6bcf\u4e2a\u7ec4\u7684\u6700\u5927\u503c\u3002\u4f8b\u5982\uff0c\u67e5\u627e\u6bcf\u4e2a\u90e8\u95e8\u7684\u6700\u9ad8\u85aa\u6c34\uff1a<\/p>\n\n\n\n
      SELECT department_id, MAX(salary) AS max_salary\nFROM employees\nGROUP BY department_id;<\/code><\/pre>\n\n\n\n
      \u793a\u4f8b\u6570\u636e<\/strong>\uff1a<\/p>\n\n\n\n
      department_id<\/th>salary<\/th><\/tr><\/thead>
      1<\/td>5000<\/td><\/tr>
      1<\/td>6000<\/td><\/tr>
      1<\/td>7000<\/td><\/tr>
      2<\/td>8000<\/td><\/tr>
      2<\/td>5500<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \u67e5\u8be2\u7ed3\u679c<\/strong>\uff1a<\/p>\n\n\n\n
      department_id<\/th>max_salary<\/th><\/tr><\/thead>
      1<\/td>7000<\/td><\/tr>
      2<\/td>8000<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      4. \u4e0e HAVING<\/code> \u5b50\u53e5\u4e00\u8d77\u4f7f\u7528<\/strong><\/h3>\n\n\n\n
      MAX()<\/code> \u51fd\u6570\u4e5f\u53ef\u4ee5\u4e0e HAVING<\/code> \u5b50\u53e5\u4e00\u8d77\u4f7f\u7528\uff0cHAVING<\/code> \u7528\u4e8e\u7b5b\u9009 GROUP BY<\/code> \u805a\u5408\u540e\u7684\u7ed3\u679c\u3002\u4f8b\u5982\uff0c\u67e5\u627e\u6bcf\u4e2a\u90e8\u95e8\u4e2d\u6700\u5927\u85aa\u6c34\u8d85\u8fc7 6000 \u7684\u90e8\u95e8\uff1a<\/p>\n\n\n\n
      SELECT department_id, MAX(salary) AS max_salary\nFROM employees\nGROUP BY department_id\nHAVING MAX(salary) > 6000;<\/code><\/pre>\n\n\n\n
      \u793a\u4f8b\u6570\u636e<\/strong>\uff1a<\/p>\n\n\n\n
      department_id<\/th>salary<\/th><\/tr><\/thead>
      1<\/td>5000<\/td><\/tr>
      1<\/td>6000<\/td><\/tr>
      1<\/td>7000<\/td><\/tr>
      2<\/td>8000<\/td><\/tr>
      2<\/td>5500<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \u67e5\u8be2\u7ed3\u679c<\/strong>\uff1a<\/p>\n\n\n\n
      department_id<\/th>max_salary<\/th><\/tr><\/thead>
      1<\/td>7000<\/td><\/tr>
      2<\/td>8000<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      5. \u5e38\u89c1\u95ee\u9898\u53ca\u89e3\u51b3\u65b9\u6848<\/strong><\/h3>\n\n\n\n
      1. MAX()<\/code> \u8fd4\u56de NULL<\/code><\/strong><\/h4>\n\n\n\n
        \n
      • \u95ee\u9898<\/strong>\uff1a\u5982\u679c\u5217\u4e2d\u7684\u6240\u6709\u503c\u90fd\u4e3a NULL<\/code>\uff0c\u5219 MAX()<\/code> \u4f1a\u8fd4\u56de NULL<\/code>\u3002<\/li>\n\n\n\n
      • \u89e3\u51b3\u65b9\u6848<\/strong>\uff1a\u53ef\u4ee5\u4f7f\u7528 COALESCE()<\/code> \u6216 IFNULL()<\/code> \u6765\u5904\u7406 NULL<\/code> \u503c\u3002\u4f8b\u5982\uff0c\u82e5\u6ca1\u6709\u85aa\u6c34\u8bb0\u5f55\uff0c\u5219\u8fd4\u56de 0<\/code>\uff1a<\/li>\n<\/ul>\n\n\n\n
          SELECT COALESCE(MAX(salary), 0) AS max_salary\n  FROM employees;<\/code><\/pre>\n\n\n\n
        2. \u5728 MAX()<\/code> \u51fd\u6570\u4e2d\u4f7f\u7528 DISTINCT<\/code><\/strong><\/h4>\n\n\n\n
          \n
        • \u95ee\u9898<\/strong>\uff1a\u4f60\u53ef\u80fd\u4f1a\u9047\u5230\u9700\u8981\u8ba1\u7b97\u67d0\u5217\u7684\u6700\u5927\u503c\uff0c\u4f46\u53c8\u5e0c\u671b\u53bb\u9664\u91cd\u590d\u7684\u503c\u3002<\/li>\n\n\n\n
        • \u89e3\u51b3\u65b9\u6848<\/strong>\uff1a\u53ef\u4ee5\u5728 MAX()<\/code> \u51fd\u6570\u4e2d\u4f7f\u7528 DISTINCT<\/code> \u6765\u4ec5\u8ba1\u7b97\u552f\u4e00\u7684\u6700\u5927\u503c\uff1a<\/li>\n<\/ul>\n\n\n\n
            SELECT MAX(DISTINCT salary) AS max_salary\n  FROM employees;<\/code><\/pre>\n\n\n\n
          3. MAX()<\/code> \u51fd\u6570\u548c\u7a7a\u503c\uff08NULL\uff09<\/strong><\/h4>\n\n\n\n
            \n
          • \u95ee\u9898<\/strong>\uff1aMAX()<\/code> \u4f1a\u5ffd\u7565 NULL<\/code> \u503c\uff0c\u5b83\u53ea\u4f1a\u8ba1\u7b97\u6709\u6548\u7684\uff08\u975e NULL<\/code>\uff09\u6570\u503c\u3002<\/li>\n\n\n\n
          • \u89e3\u51b3\u65b9\u6848<\/strong>\uff1a\u786e\u4fdd\u5904\u7406 NULL<\/code> \u503c\u3002\u5982\u679c\u4f60\u60f3\u8ba1\u7b97\u5305\u542b NULL<\/code> \u7684\u5217\u7684\u6700\u5927\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528\u6761\u4ef6\u67e5\u8be2\u6216 COALESCE()<\/code> \u6765\u5c06 NULL<\/code> \u8f6c\u6362\u4e3a\u5176\u4ed6\u9ed8\u8ba4\u503c\uff1a<\/li>\n<\/ul>\n\n\n\n
              SELECT MAX(COALESCE(salary, 0)) AS max_salary\n  FROM employees;<\/code><\/pre>\n\n\n\n
            4. MAX()<\/code> \u548c\u6587\u672c\u5217<\/strong><\/h4>\n\n\n\n
              \n
            • \u95ee\u9898<\/strong>\uff1aMAX()<\/code> \u51fd\u6570\u8fd4\u56de\u5b57\u7b26\u4e32\u5217\u7684\u6700\u5927\u503c\u662f\u6309\u5b57\u5178\u987a\u5e8f\uff08ASCII \u503c\u987a\u5e8f\uff09\u8fdb\u884c\u6392\u5e8f\u7684\u3002<\/li>\n\n\n\n
            • \u89e3\u51b3\u65b9\u6848<\/strong>\uff1a\u5982\u679c\u9700\u8981\u6309\u5b57\u6bcd\u987a\u5e8f\u83b7\u53d6\u6587\u672c\u5217\u7684\u6700\u5927\u503c\uff0cMAX()<\/code> \u51fd\u6570\u662f\u6709\u6548\u7684\u3002\u786e\u4fdd\u4f60\u7406\u89e3\u5b83\u662f\u6309\u5b57\u5178\u987a\u5e8f\u6392\u5e8f\u7684\u3002\u5982\u679c\u9700\u8981\u4e0d\u540c\u7684\u6392\u5e8f\u987a\u5e8f\uff0c\u53ef\u4ee5\u4f7f\u7528 ORDER BY<\/code> \u8fdb\u884c\u8c03\u6574\u3002<\/li>\n<\/ul>\n\n\n\n
              5. \u8ba1\u7b97\u67d0\u4e00\u7ec4\u4e2d\u6700\u5927\u503c\u7684\u65f6\u95f4\u590d\u6742\u5ea6<\/strong><\/h4>\n\n\n\n
                \n
              • \u95ee\u9898<\/strong>\uff1aMAX()<\/code> \u51fd\u6570\u5728\u8ba1\u7b97\u805a\u5408\u503c\u65f6\uff0c\u53ef\u80fd\u5728\u975e\u5e38\u5927\u7684\u6570\u636e\u96c6\u4e0a\u6027\u80fd\u4e0d\u7406\u60f3\uff0c\u5c24\u5176\u662f\u5728\u6ca1\u6709\u7d22\u5f15\u7684\u60c5\u51b5\u4e0b\u3002<\/li>\n\n\n\n
              • \u89e3\u51b3\u65b9\u6848<\/strong>\uff1a\u786e\u4fdd\u5bf9\u9700\u8981\u8ba1\u7b97 MAX()<\/code> \u7684\u5217\u521b\u5efa\u7d22\u5f15\uff0c\u5c24\u5176\u662f\u5f53\u8be5\u5217\u7528\u4e8e WHERE<\/code> \u6216 ORDER BY<\/code> \u5b50\u53e5\u65f6\u3002<\/li>\n<\/ul>\n\n\n\n
                6. \u4e0e\u5176\u4ed6\u805a\u5408\u51fd\u6570\u4e00\u8d77\u4f7f\u7528<\/strong><\/h3>\n\n\n\n
                MAX()<\/code> \u53ef\u4ee5\u4e0e\u5176\u4ed6\u805a\u5408\u51fd\u6570\u4e00\u8d77\u4f7f\u7528\uff0c\u5982 AVG()<\/code>, SUM()<\/code>, COUNT()<\/code> \u7b49\u3002\u4f8b\u5982\uff0c\u4f60\u53ef\u80fd\u9700\u8981\u67e5\u8be2\u6bcf\u4e2a\u90e8\u95e8\u7684\u6700\u5927\u85aa\u6c34\u3001\u5e73\u5747\u85aa\u6c34\u4ee5\u53ca\u5458\u5de5\u603b\u6570\uff1a<\/p>\n\n\n\n
                SELECT department_id,\n       MAX(salary) AS max_salary,\n       AVG(salary) AS avg_salary,\n       COUNT(*) AS employee_count\nFROM employees\nGROUP BY department_id;<\/code><\/pre>\n\n\n\n
                7. \u603b\u7ed3<\/strong><\/h3>\n\n\n\n
                  \n
                • MAX()<\/code> \u51fd\u6570\u7528\u4e8e\u8fd4\u56de\u67d0\u5217\u7684\u6700\u5927\u503c\uff0c\u652f\u6301\u6570\u503c\u3001\u65e5\u671f\u548c\u5b57\u7b26\u6570\u636e\u7c7b\u578b\u3002<\/li>\n\n\n\n
                • \u5b83\u5e7f\u6cdb\u5e94\u7528\u4e8e\u8ba1\u7b97\u6570\u636e\u7684\u6700\u5927\u503c\uff0c\u5e76\u5e38\u4e0e GROUP BY<\/code> \u548c HAVING<\/code> \u5b50\u53e5\u7ed3\u5408\u4f7f\u7528\u3002<\/li>\n\n\n\n
                • \u5728\u5904\u7406\u7a7a\u503c\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528 COALESCE()<\/code> \u6216 IFNULL()<\/code> \u6765\u907f\u514d\u8fd4\u56de NULL<\/code>\u3002<\/li>\n\n\n\n
                • \u5728\u975e\u5e38\u5927\u7684\u6570\u636e\u96c6\u4e0a\uff0c\u786e\u4fdd\u5bf9\u76f8\u5173\u5217\u521b\u5efa\u7d22\u5f15\uff0c\u4ee5\u63d0\u9ad8\u6027\u80fd\u3002<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
                  MAX() \u51fd\u6570\u662f\u4e00\u4e2a\u805a\u5408\u51fd\u6570\uff0c\u7528\u4e8e\u8fd4\u56de\u6307\u5b9a\u5217\u4e2d\u7684\u6700\u5927\u503c\u3002\u5b83\u5e7f\u6cdb\u5e94\u7528\u4e8e SQL \u67e5\u8be2\u4e2d\uff0c\u5c24\u5176\u662f\u7528\u4e8e\u67e5\u627e\u6570\u636e\u96c6\u4e2d […]<\/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":[],"class_list":["post-1721","post","type-post","status-publish","format-standard","hentry","category-sql"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1721","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=1721"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1721\/revisions"}],"predecessor-version":[{"id":1722,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1721\/revisions\/1722"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=1721"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=1721"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=1721"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}