{"id":1506,"date":"2025-02-10T23:32:11","date_gmt":"2025-02-10T15:32:11","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=1506"},"modified":"2025-02-10T23:32:12","modified_gmt":"2025-02-10T15:32:12","slug":"sql%e5%9f%ba%e7%a1%80%e5%85%a5%e9%97%a8%e6%95%99%e7%a8%8b%ef%bc%9a%e4%bb%8e%e9%9b%b6%e5%bc%80%e5%a7%8b%e5%ad%a6%e4%b9%a0sql%e6%9f%a5%e8%af%a2%e4%b8%8e%e6%95%b0%e6%8d%ae%e6%93%8d%e4%bd%9c","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/02\/10\/sql%e5%9f%ba%e7%a1%80%e5%85%a5%e9%97%a8%e6%95%99%e7%a8%8b%ef%bc%9a%e4%bb%8e%e9%9b%b6%e5%bc%80%e5%a7%8b%e5%ad%a6%e4%b9%a0sql%e6%9f%a5%e8%af%a2%e4%b8%8e%e6%95%b0%e6%8d%ae%e6%93%8d%e4%bd%9c\/","title":{"rendered":"SQL\u57fa\u7840\u5165\u95e8\u6559\u7a0b\uff1a\u4ece\u96f6\u5f00\u59cb\u5b66\u4e60SQL\u67e5\u8be2\u4e0e\u6570\u636e\u64cd\u4f5c"},"content":{"rendered":"\n

1. SQL\u7b80\u4ecb<\/strong><\/h3>\n\n\n\n

1.1 \u4ec0\u4e48\u662fSQL\uff1f<\/h4>\n\n\n\n

SQL\uff08Structured Query Language\uff09\u662f\u7528\u4e8e\u7ba1\u7406\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7684\u6807\u51c6\u8bed\u8a00\u3002\u5b83\u5141\u8bb8\u7528\u6237\u67e5\u8be2\u3001\u66f4\u65b0\u3001\u63d2\u5165\u548c\u5220\u9664\u6570\u636e\u5e93\u4e2d\u7684\u6570\u636e\u3002SQL \u662f\u4e0e\u6570\u636e\u5e93\u4ea4\u4e92\u7684\u6838\u5fc3\u5de5\u5177\uff0c\u53ef\u4ee5\u7528\u6765\u6267\u884c\u6240\u6709\u4e0e\u6570\u636e\u76f8\u5173\u7684\u64cd\u4f5c\u3002<\/p>\n\n\n\n

1.2 SQL\u7684\u5386\u53f2\u4e0e\u53d1\u5c55<\/h4>\n\n\n\n

SQL \u57281970\u5e74\u4ee3\u7531 IBM \u7684\u7814\u7a76\u4eba\u5458\u5f00\u53d1\uff0c\u5e76\u88ab\u79f0\u4e3a SEQUEL\uff08Structured English Query Language\uff09\u3002\u5b83\u4ece\u6700\u521d\u7684\u5173\u7cfb\u6570\u636e\u5e93\u6a21\u578b\u4e2d\u884d\u751f\u800c\u6765\uff0c\u5e76\u57281986\u5e74\u88ab ANSI\uff08\u7f8e\u56fd\u56fd\u5bb6\u6807\u51c6\u534f\u4f1a\uff09\u6b63\u5f0f\u6807\u51c6\u5316\u3002\u5982\u4eca\uff0cSQL \u5df2\u6210\u4e3a\u6700\u5e7f\u6cdb\u4f7f\u7528\u7684\u6570\u636e\u5e93\u67e5\u8be2\u8bed\u8a00\u3002<\/p>\n\n\n\n

1.3 SQL\u4e0e\u6570\u636e\u5e93\u7684\u5173\u7cfb<\/h4>\n\n\n\n

SQL \u4e3b\u8981\u4e0e\u5173\u7cfb\u578b\u6570\u636e\u5e93\uff08RDBMS\uff09\u914d\u5408\u4f7f\u7528\uff0c\u5982 MySQL\u3001PostgreSQL\u3001SQL Server \u548c Oracle\u3002\u901a\u8fc7 SQL\uff0c\u7528\u6237\u80fd\u591f\u6267\u884c\u5404\u79cd\u6570\u636e\u7ba1\u7406\u64cd\u4f5c\uff0c\u5e76\u4e0e\u6570\u636e\u5e93\u7cfb\u7edf\u4ea4\u4e92\u3002<\/p>\n\n\n\n

2. \u57fa\u672c\u6570\u636e\u7c7b\u578b<\/strong><\/h3>\n\n\n\n

\u6570\u636e\u5e93\u4e2d\u7684\u6570\u636e\u53ef\u4ee5\u91c7\u7528\u4e0d\u540c\u7684\u6570\u636e\u7c7b\u578b\uff0c\u4ee5\u4e0b\u662f SQL \u4e2d\u5e38\u89c1\u7684\u6570\u636e\u7c7b\u578b\uff1a<\/p>\n\n\n\n

    \n
  • \u6574\u6570\u7c7b\u578b<\/strong>\uff08\u5982 INT<\/code>\uff09\uff1a\u5b58\u50a8\u6574\u6570\u6570\u503c\u3002<\/li>\n\n\n\n
  • \u6d6e\u52a8\u70b9\u6570\u7c7b\u578b<\/strong>\uff08\u5982 FLOAT<\/code>, DECIMAL<\/code>\uff09\uff1a\u5b58\u50a8\u5c0f\u6570\u6216\u6d6e\u52a8\u5c0f\u6570\u3002<\/li>\n\n\n\n
  • \u5b57\u7b26\u7c7b\u578b<\/strong>\uff08\u5982 CHAR<\/code>, VARCHAR<\/code>\uff09\uff1a\u5b58\u50a8\u5b57\u7b26\u4e32\u6216\u6587\u672c\u3002<\/li>\n\n\n\n
  • \u65e5\u671f\u4e0e\u65f6\u95f4\u7c7b\u578b<\/strong>\uff08\u5982 DATE<\/code>, TIME<\/code>, DATETIME<\/code>\uff09\uff1a\u5b58\u50a8\u65e5\u671f\u548c\u65f6\u95f4\u3002<\/li>\n<\/ul>\n\n\n\n

    \u793a\u4f8b\uff1a<\/p>\n\n\n\n

    CREATE TABLE users (\n    id INT,\n    name VARCHAR(100),\n    birth_date DATE\n);<\/code><\/pre>\n\n\n\n
    3. \u57fa\u672c\u67e5\u8be2<\/strong><\/h3>\n\n\n\n
    3.1 SELECT\u8bed\u53e5<\/h4>\n\n\n\n
    SELECT<\/code> \u8bed\u53e5\u7528\u4e8e\u4ece\u6570\u636e\u5e93\u4e2d\u67e5\u8be2\u6570\u636e\u3002\u5b83\u662f SQL \u6700\u57fa\u672c\u7684\u8bed\u53e5\u3002<\/p>\n\n\n\n
      \n
    • \u67e5\u8be2\u6240\u6709\u5217\uff1a<\/li>\n<\/ul>\n\n\n\n
      SELECT * FROM users;<\/code><\/pre>\n\n\n\n
        \n
      • \u67e5\u8be2\u7279\u5b9a\u5217\uff1a<\/li>\n<\/ul>\n\n\n\n
        SELECT name, birth_date FROM users;<\/code><\/pre>\n\n\n\n
        3.2 \u67e5\u8be2\u7279\u5b9a\u5217\u4e0e\u884c<\/h4>\n\n\n\n
        \u901a\u8fc7\u4f7f\u7528 WHERE<\/code> \u5b50\u53e5\uff0c\u53ef\u4ee5\u6307\u5b9a\u67e5\u8be2\u7684\u884c\u3002<\/p>\n\n\n\n
          \n
        • \u67e5\u8be2\u7279\u5b9a\u6761\u4ef6\u7684\u6570\u636e\uff1a<\/li>\n<\/ul>\n\n\n\n
          SELECT * FROM users WHERE id = 1;<\/code><\/pre>\n\n\n\n
          3.3 \u4f7f\u7528 WHERE \u6761\u4ef6<\/h4>\n\n\n\n
          WHERE<\/code> \u5b50\u53e5\u7528\u4e8e\u8fc7\u6ee4\u67e5\u8be2\u7ed3\u679c\uff0c\u5141\u8bb8\u6839\u636e\u6761\u4ef6\u7b5b\u9009\u6570\u636e\u3002<\/p>\n\n\n\n
            \n
          • \u67e5\u8be2\u540d\u5b57\u4e3a “John” \u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
            SELECT * FROM users WHERE name = 'John';<\/code><\/pre>\n\n\n\n
            3.4 \u6392\u5e8f\uff1aORDER BY<\/h4>\n\n\n\n
            ORDER BY<\/code> \u7528\u4e8e\u6392\u5e8f\u67e5\u8be2\u7ed3\u679c\uff0c\u9ed8\u8ba4\u6309\u5347\u5e8f\u6392\u5e8f\uff08ASC<\/code>\uff09\uff0c\u4e5f\u53ef\u4ee5\u6307\u5b9a\u964d\u5e8f\uff08DESC<\/code>\uff09\u3002<\/p>\n\n\n\n
              \n
            • \u6309\u540d\u5b57\u5347\u5e8f\u6392\u5e8f\uff1a<\/li>\n<\/ul>\n\n\n\n
              SELECT * FROM users ORDER BY name ASC;<\/code><\/pre>\n\n\n\n
                \n
              • \u6309\u51fa\u751f\u65e5\u671f\u964d\u5e8f\u6392\u5e8f\uff1a<\/li>\n<\/ul>\n\n\n\n
                SELECT * FROM users ORDER BY birth_date DESC;<\/code><\/pre>\n\n\n\n
                4. \u805a\u5408\u51fd\u6570<\/strong><\/h3>\n\n\n\n
                \u805a\u5408\u51fd\u6570\u7528\u4e8e\u6267\u884c\u6c47\u603b\u8ba1\u7b97\uff0c\u5e38\u89c1\u7684\u805a\u5408\u51fd\u6570\u5305\u62ec\uff1aCOUNT()<\/code>\u3001SUM()<\/code>\u3001AVG()<\/code>\u3001MIN()<\/code> \u548c MAX()<\/code>\u3002<\/p>\n\n\n\n
                4.1 COUNT() \u51fd\u6570<\/h4>\n\n\n\n
                \u7528\u4e8e\u7edf\u8ba1\u67d0\u5217\u7684\u8bb0\u5f55\u6570\u3002<\/p>\n\n\n\n
                SELECT COUNT(*) FROM users;<\/code><\/pre>\n\n\n\n
                4.2 SUM() \u51fd\u6570<\/h4>\n\n\n\n
                \u7528\u4e8e\u8ba1\u7b97\u67d0\u5217\u7684\u603b\u548c\u3002<\/p>\n\n\n\n
                SELECT SUM(age) FROM users;<\/code><\/pre>\n\n\n\n
                4.3 AVG() \u51fd\u6570<\/h4>\n\n\n\n
                \u7528\u4e8e\u8ba1\u7b97\u67d0\u5217\u7684\u5e73\u5747\u503c\u3002<\/p>\n\n\n\n
                SELECT AVG(age) FROM users;<\/code><\/pre>\n\n\n\n
                4.4 MIN() \u548c MAX() \u51fd\u6570<\/h4>\n\n\n\n
                \u5206\u522b\u8fd4\u56de\u67d0\u5217\u7684\u6700\u5c0f\u503c\u548c\u6700\u5927\u503c\u3002<\/p>\n\n\n\n
                SELECT MIN(age), MAX(age) FROM users;<\/code><\/pre>\n\n\n\n
                4.5 \u4f7f\u7528 GROUP BY \u5206\u7ec4\u6570\u636e<\/h4>\n\n\n\n
                GROUP BY<\/code> \u5b50\u53e5\u7528\u4e8e\u5c06\u67e5\u8be2\u7ed3\u679c\u6309\u7167\u67d0\u5217\u8fdb\u884c\u5206\u7ec4\uff0c\u5e76\u5bf9\u6bcf\u7ec4\u6570\u636e\u5e94\u7528\u805a\u5408\u51fd\u6570\u3002<\/p>\n\n\n\n
                  \n
                • \u6309\u5e74\u9f84\u5206\u7ec4\uff0c\u7edf\u8ba1\u6bcf\u4e2a\u5e74\u9f84\u6bb5\u7684\u4eba\u6570\uff1a<\/li>\n<\/ul>\n\n\n\n
                  SELECT age, COUNT(*) FROM users GROUP BY age;<\/code><\/pre>\n\n\n\n
                  4.6 \u4f7f\u7528 HAVING \u8fc7\u6ee4\u805a\u5408\u7ed3\u679c<\/h4>\n\n\n\n
                  HAVING<\/code> \u5b50\u53e5\u7528\u4e8e\u5728 GROUP BY<\/code> \u540e\u5bf9\u5206\u7ec4\u7684\u7ed3\u679c\u8fdb\u884c\u8fc7\u6ee4\u3002<\/p>\n\n\n\n
                    \n
                  • \u53ea\u9009\u62e9\u4eba\u6570\u5927\u4e8e1\u7684\u5e74\u9f84\u6bb5\uff1a<\/li>\n<\/ul>\n\n\n\n
                    SELECT age, COUNT(*) FROM users GROUP BY age HAVING COUNT(*) > 1;<\/code><\/pre>\n\n\n\n
                    5. \u6570\u636e\u8fc7\u6ee4<\/strong><\/h3>\n\n\n\n
                    5.1 \u4f7f\u7528 AND\u3001OR\u3001NOT \u8fdb\u884c\u590d\u5408\u6761\u4ef6\u67e5\u8be2<\/h4>\n\n\n\n
                    \u53ef\u4ee5\u4f7f\u7528 AND<\/code>\u3001OR<\/code> \u548c NOT<\/code> \u6765\u7ec4\u5408\u591a\u4e2a\u6761\u4ef6\u3002<\/p>\n\n\n\n
                      \n
                    • \u67e5\u8be2\u5e74\u9f84\u5927\u4e8e20\u4e14\u540d\u5b57\u4e3a “John” \u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                      SELECT * FROM users WHERE age > 20 AND name = 'John';<\/code><\/pre>\n\n\n\n
                        \n
                      • \u67e5\u8be2\u540d\u5b57\u4e3a “John” \u6216 “Jane” \u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                        SELECT * FROM users WHERE name = 'John' OR name = 'Jane';<\/code><\/pre>\n\n\n\n
                          \n
                        • \u67e5\u8be2\u4e0d\u5305\u542b\u540d\u5b57 “John” \u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                          SELECT * FROM users WHERE NOT name = 'John';<\/code><\/pre>\n\n\n\n
                          5.2 BETWEEN \u64cd\u4f5c\u7b26<\/h4>\n\n\n\n
                          BETWEEN<\/code> \u7528\u4e8e\u67e5\u627e\u6307\u5b9a\u8303\u56f4\u5185\u7684\u6570\u636e\u3002<\/p>\n\n\n\n
                            \n
                          • \u67e5\u8be2\u5e74\u9f84\u5728 20 \u5230 30 \u4e4b\u95f4\u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                            SELECT * FROM users WHERE age BETWEEN 20 AND 30;<\/code><\/pre>\n\n\n\n
                            5.3 IN \u64cd\u4f5c\u7b26<\/h4>\n\n\n\n
                            IN<\/code> \u7528\u4e8e\u5339\u914d\u6307\u5b9a\u7684\u591a\u4e2a\u503c\u3002<\/p>\n\n\n\n
                              \n
                            • \u67e5\u8be2\u540d\u5b57\u662f “John” \u6216 “Jane” \u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                              SELECT * FROM users WHERE name IN ('John', 'Jane');<\/code><\/pre>\n\n\n\n
                              5.4 LIKE \u64cd\u4f5c\u7b26<\/h4>\n\n\n\n
                              LIKE<\/code> \u7528\u4e8e\u6a21\u5f0f\u5339\u914d\uff0c\u901a\u5e38\u7528\u4e8e\u6a21\u7cca\u67e5\u8be2\u3002<\/p>\n\n\n\n
                                \n
                              • \u67e5\u8be2\u540d\u5b57\u4ee5 “J” \u5f00\u5934\u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                                SELECT * FROM users WHERE name LIKE 'J%';<\/code><\/pre>\n\n\n\n
                                  \n
                                • \u67e5\u8be2\u540d\u5b57\u5305\u542b “an” \u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                                  SELECT * FROM users WHERE name LIKE '%an%';<\/code><\/pre>\n\n\n\n
                                  5.5 IS NULL \u64cd\u4f5c\u7b26<\/h4>\n\n\n\n
                                  IS NULL<\/code> \u7528\u4e8e\u67e5\u627e\u7a7a\u503c\u3002<\/p>\n\n\n\n
                                    \n
                                  • \u67e5\u8be2\u6ca1\u6709\u51fa\u751f\u65e5\u671f\u7684\u7528\u6237\uff1a<\/li>\n<\/ul>\n\n\n\n
                                    SELECT * FROM users WHERE birth_date IS NULL;<\/code><\/pre>\n\n\n\n
                                    \n\n\n\n
                                    \u603b\u7ed3<\/h3>\n\n\n\n
                                    \u4ee5\u4e0a\u662f SQL \u57fa\u7840\u90e8\u5206\u7684\u8be6\u7ec6\u6559\u7a0b\uff0c\u6db5\u76d6\u4e86 SQL \u7684\u6838\u5fc3\u6982\u5ff5\u4e0e\u5e38\u7528\u64cd\u4f5c\uff0c\u5305\u62ec\u67e5\u8be2\u3001\u6570\u636e\u8fc7\u6ee4\u3001\u6392\u5e8f\u3001\u805a\u5408\u3001\u4ee5\u53ca\u6570\u636e\u5206\u7ec4\u7b49\u3002\u638c\u63e1\u8fd9\u4e9b\u57fa\u7840\u5185\u5bb9\u540e\uff0c\u4f60\u5c06\u80fd\u591f\u5728 SQL \u6570\u636e\u5e93\u4e2d\u6267\u884c\u9ad8\u6548\u7684\u67e5\u8be2\u4e0e\u64cd\u4f5c\uff0c\u4e3a\u8fdb\u4e00\u6b65\u6df1\u5165\u5b66\u4e60 SQL \u548c\u9ad8\u7ea7\u6570\u636e\u5e93\u7ba1\u7406\u6253\u4e0b\u575a\u5b9e\u7684\u57fa\u7840\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
                                    1. SQL\u7b80\u4ecb 1.1 \u4ec0\u4e48\u662fSQL\uff1f SQL\uff08Structured Query Language\uff09\u662f\u7528\u4e8e\u7ba1 […]<\/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-1506","post","type-post","status-publish","format-standard","hentry","category-sql"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1506","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=1506"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1506\/revisions"}],"predecessor-version":[{"id":1507,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1506\/revisions\/1507"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=1506"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=1506"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=1506"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}