{"id":2322,"date":"2025-03-04T08:38:16","date_gmt":"2025-03-04T00:38:16","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=2322"},"modified":"2025-03-04T08:38:16","modified_gmt":"2025-03-04T00:38:16","slug":"sqlite-%e8%a1%a8%e8%be%be%e5%bc%8f","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/03\/04\/sqlite-%e8%a1%a8%e8%be%be%e5%bc%8f\/","title":{"rendered":"SQLite \u8868\u8fbe\u5f0f"},"content":{"rendered":"\n
\n

\u5728 SQLite \u4e2d\uff0c\u8868\u8fbe\u5f0f<\/strong>\u662f\u901a\u8fc7\u8fd0\u7b97\u7b26\u3001\u5e38\u91cf\u3001\u5217\u540d\u548c\u51fd\u6570\u7ec4\u5408\u8d77\u6765\u7684\u3002\u5b83\u4eec\u5728 SQL \u67e5\u8be2\u4e2d\u7528\u4e8e\u751f\u6210\u6216\u8ba1\u7b97\u4e00\u4e2a\u503c\u3002\u5e38\u89c1\u7684\u8868\u8fbe\u5f0f\u6709\u7b97\u672f\u8868\u8fbe\u5f0f\u3001\u5b57\u7b26\u4e32\u8868\u8fbe\u5f0f\u3001\u65e5\u671f\u548c\u65f6\u95f4\u8868\u8fbe\u5f0f\u7b49\u3002<\/p>\n<\/blockquote>\n\n\n\n

1. \u7b97\u672f\u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n

\u7b97\u672f\u8868\u8fbe\u5f0f\u7528\u4e8e\u8fdb\u884c\u6570\u503c\u8ba1\u7b97\u3002\u5b83\u4eec\u4f7f\u7528\u57fa\u672c\u7684\u7b97\u672f\u8fd0\u7b97\u7b26\uff0c\u5982 +<\/code>\u3001-<\/code>\u3001*<\/code> \u548c \/<\/code>\u3002<\/p>\n\n\n\n

\u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
SELECT price + tax AS total_price FROM products;<\/code><\/pre>\n\n\n\n
    \n
  • \u8be5\u8868\u8fbe\u5f0f\u8ba1\u7b97\u4e86\u6bcf\u4e2a\u4ea7\u54c1\u7684 price<\/code> \u4e0e tax<\/code> \u7684\u603b\u548c\uff0c\u7ed3\u679c\u547d\u540d\u4e3a total_price<\/code>\u3002<\/li>\n<\/ul>\n\n\n\n
    2. \u5b57\u7b26\u4e32\u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
    \u5b57\u7b26\u4e32\u8868\u8fbe\u5f0f\u7528\u4e8e\u5b57\u7b26\u4e32\u7684\u62fc\u63a5\u6216\u4fee\u6539\u3002SQLite \u4f7f\u7528 ||<\/code> \u8fd0\u7b97\u7b26\u6765\u8fde\u63a5\u5b57\u7b26\u4e32\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
    SELECT first_name || ' ' || last_name AS full_name FROM employees;<\/code><\/pre>\n\n\n\n
      \n
    • \u8be5\u8868\u8fbe\u5f0f\u5c06 first_name<\/code> \u548c last_name<\/code> \u5b57\u6bb5\u8fde\u63a5\u6210\u4e00\u4e2a\u5b8c\u6574\u7684\u540d\u5b57\uff0c\u5e76\u547d\u540d\u4e3a full_name<\/code>\u3002<\/li>\n<\/ul>\n\n\n\n
      3. \u6bd4\u8f83\u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
      \u6bd4\u8f83\u8868\u8fbe\u5f0f\u7528\u4e8e\u6bd4\u8f83\u503c\uff0c\u8fd4\u56de TRUE<\/code>\u3001FALSE<\/code> \u6216 NULL<\/code>\u3002\u5e38\u7528\u7684\u6bd4\u8f83\u8fd0\u7b97\u7b26\u6709 =<\/code>, !=<\/code>, ><\/code>, <<\/code>, >=<\/code>, <=<\/code> \u7b49\u3002<\/p>\n\n\n\n
      \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
      SELECT * FROM users WHERE age > 30;<\/code><\/pre>\n\n\n\n
        \n
      • \u8be5\u8868\u8fbe\u5f0f\u7528\u4e8e\u6bd4\u8f83 age<\/code> \u662f\u5426\u5927\u4e8e 30\uff0c\u8fd4\u56de\u7b26\u5408\u6761\u4ef6\u7684\u6240\u6709\u8bb0\u5f55\u3002<\/li>\n<\/ul>\n\n\n\n
        4. \u903b\u8f91\u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
        \u903b\u8f91\u8868\u8fbe\u5f0f\u7528\u4e8e\u8fde\u63a5\u591a\u4e2a\u6761\u4ef6\uff0c\u901a\u5e38\u4e0e AND<\/code>, OR<\/code>, NOT<\/code> \u7b49\u903b\u8f91\u8fd0\u7b97\u7b26\u4e00\u8d77\u4f7f\u7528\u3002<\/p>\n\n\n\n
        \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
        SELECT * FROM users WHERE age > 20 AND name LIKE 'A%';<\/code><\/pre>\n\n\n\n
          \n
        • \u8be5\u8868\u8fbe\u5f0f\u8fd4\u56de\u5e74\u9f84\u5927\u4e8e 20 \u5e76\u4e14\u59d3\u540d\u4ee5 ‘A’ \u5f00\u5934\u7684\u6240\u6709\u7528\u6237\u3002<\/li>\n<\/ul>\n\n\n\n
          5. CASE<\/code> \u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
          CASE<\/code> \u8868\u8fbe\u5f0f\u662f SQLite \u4e2d\u7684\u6761\u4ef6\u8868\u8fbe\u5f0f\uff0c\u7528\u4e8e\u5728 SQL \u67e5\u8be2\u4e2d\u6839\u636e\u6761\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u503c\u3002<\/p>\n\n\n\n
          \u8bed\u6cd5\uff1a<\/strong><\/h4>\n\n\n\n
          SELECT CASE\n         WHEN condition THEN result\n         WHEN condition THEN result\n         ELSE result\n       END\nFROM table_name;<\/code><\/pre>\n\n\n\n
          \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
          SELECT name, \n       CASE\n         WHEN age < 18 THEN 'Minor'\n         WHEN age >= 18 AND age < 60 THEN 'Adult'\n         ELSE 'Senior'\n       END AS age_group\nFROM users;<\/code><\/pre>\n\n\n\n
            \n
          • \u8be5\u8868\u8fbe\u5f0f\u6839\u636e age<\/code> \u5217\u7684\u503c\uff0c\u8fd4\u56de\u4e0d\u540c\u7684\u5e74\u9f84\u7ec4\u6807\u7b7e\uff08Minor<\/code>, Adult<\/code>, Senior<\/code>\uff09\u3002<\/li>\n<\/ul>\n\n\n\n
            6. \u805a\u5408\u51fd\u6570\u4f5c\u4e3a\u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
            \u805a\u5408\u51fd\u6570\u5982 COUNT()<\/code>, SUM()<\/code>, AVG()<\/code>, MIN()<\/code>, MAX()<\/code> \u4e5f\u53ef\u4ee5\u4f5c\u4e3a\u8868\u8fbe\u5f0f\u7528\u4e8e\u8ba1\u7b97\u4e00\u7ec4\u6570\u636e\u7684\u6c47\u603b\u503c\u3002<\/p>\n\n\n\n
            \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
            SELECT AVG(age) FROM users;<\/code><\/pre>\n\n\n\n
              \n
            • \u8be5\u8868\u8fbe\u5f0f\u8ba1\u7b97 users<\/code> \u8868\u4e2d age<\/code> \u5217\u7684\u5e73\u5747\u503c\u3002<\/li>\n<\/ul>\n\n\n\n
              7. \u65e5\u671f\u548c\u65f6\u95f4\u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
              SQLite \u63d0\u4f9b\u4e86\u591a\u79cd\u7528\u4e8e\u5904\u7406\u65e5\u671f\u548c\u65f6\u95f4\u7684\u51fd\u6570\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528 DATE()<\/code>\u3001TIME()<\/code>\u3001DATETIME()<\/code> \u7b49\u51fd\u6570\uff0c\u6216\u8005\u76f4\u63a5\u8fdb\u884c\u65e5\u671f\u8ba1\u7b97\u3002<\/p>\n\n\n\n
              \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
              SELECT DATE('now');<\/code><\/pre>\n\n\n\n
                \n
              • \u8be5\u8868\u8fbe\u5f0f\u8fd4\u56de\u5f53\u524d\u65e5\u671f\u3002<\/li>\n<\/ul>\n\n\n\n
                SELECT DATE('now', '+1 day');<\/code><\/pre>\n\n\n\n
                  \n
                • \u8be5\u8868\u8fbe\u5f0f\u8fd4\u56de\u660e\u5929\u7684\u65e5\u671f\u3002<\/li>\n<\/ul>\n\n\n\n
                  8. IFNULL<\/code> \u548c COALESCE<\/code> \u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
                    \n
                  • IFNULL()<\/code>\uff1a\u7528\u4e8e\u66ff\u6362 NULL<\/code> \u503c\u3002<\/li>\n\n\n\n
                  • COALESCE()<\/code>\uff1a\u8fd4\u56de\u7b2c\u4e00\u4e2a\u975e NULL<\/code> \u7684\u503c\u3002<\/li>\n<\/ul>\n\n\n\n
                    \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
                    SELECT IFNULL(age, 0) FROM users;<\/code><\/pre>\n\n\n\n
                      \n
                    • \u8be5\u8868\u8fbe\u5f0f\u4f1a\u5c06 age<\/code> \u4e3a NULL<\/code> \u7684\u503c\u66ff\u6362\u4e3a 0<\/code>\u3002<\/li>\n<\/ul>\n\n\n\n
                      SELECT COALESCE(age, 0, 18) FROM users;<\/code><\/pre>\n\n\n\n
                        \n
                      • \u8be5\u8868\u8fbe\u5f0f\u4f1a\u5c06 age<\/code> \u4e3a NULL<\/code> \u7684\u503c\u66ff\u6362\u4e3a 0<\/code>\uff0c\u5982\u679c age<\/code> \u8fd8\u662f NULL<\/code>\uff0c\u5219\u8fd4\u56de 18<\/code>\u3002<\/li>\n<\/ul>\n\n\n\n
                        9. CAST<\/code> \u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
                        CAST<\/code> \u7528\u4e8e\u5c06\u4e00\u4e2a\u503c\u4ece\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u8f6c\u6362\u4e3a\u53e6\u4e00\u79cd\u6570\u636e\u7c7b\u578b\u3002<\/p>\n\n\n\n
                        \u8bed\u6cd5\uff1a<\/strong><\/h4>\n\n\n\n
                        CAST(expression AS target_data_type)<\/code><\/pre>\n\n\n\n
                        \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
                        SELECT CAST(price AS TEXT) FROM products;<\/code><\/pre>\n\n\n\n
                          \n
                        • \u8be5\u8868\u8fbe\u5f0f\u5c06 price<\/code> \u5b57\u6bb5\u7684\u503c\u8f6c\u6362\u4e3a TEXT<\/code> \u7c7b\u578b\u3002<\/li>\n<\/ul>\n\n\n\n
                          10. \u5b50\u67e5\u8be2\u4f5c\u4e3a\u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n
                          \u5b50\u67e5\u8be2\u53ef\u4ee5\u4f5c\u4e3a\u4e00\u4e2a\u8868\u8fbe\u5f0f\u5728\u4e3b\u67e5\u8be2\u4e2d\u4f7f\u7528\u3002\u5b50\u67e5\u8be2\u8fd4\u56de\u7684\u7ed3\u679c\u53ef\u4ee5\u76f4\u63a5\u7528\u4e8e\u7236\u67e5\u8be2\u7684\u5b57\u6bb5\u6216\u6761\u4ef6\u4e2d\u3002<\/p>\n\n\n\n
                          \u793a\u4f8b\uff1a<\/strong><\/h4>\n\n\n\n
                          SELECT name, age \nFROM users \nWHERE age > (SELECT AVG(age) FROM users);<\/code><\/pre>\n\n\n\n
                            \n
                          • \u8be5\u8868\u8fbe\u5f0f\u67e5\u8be2\u5e74\u9f84\u5927\u4e8e\u6240\u6709\u7528\u6237\u5e73\u5747\u5e74\u9f84\u7684\u7528\u6237\u3002<\/li>\n<\/ul>\n\n\n\n
                            \n\n\n\n
                            \u603b\u7ed3<\/strong><\/h2>\n\n\n\n
                            SQLite \u4e2d\u7684\u8868\u8fbe\u5f0f\u7528\u4e8e\u8fdb\u884c\u5404\u79cd\u64cd\u4f5c\uff0c\u4ece\u57fa\u672c\u7684\u7b97\u672f\u8ba1\u7b97\u5230\u590d\u6742\u7684\u6761\u4ef6\u5224\u65ad\uff0c\u751a\u81f3\u6d89\u53ca\u65e5\u671f\u3001\u65f6\u95f4\u7684\u64cd\u4f5c\u3002\u5e38\u89c1\u7684\u8868\u8fbe\u5f0f\u7c7b\u578b\u5305\u62ec\uff1a<\/p>\n\n\n\n
                              \n
                            • \u7b97\u672f\u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • \u5b57\u7b26\u4e32\u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • \u6bd4\u8f83\u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • \u903b\u8f91\u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • CASE<\/code> \u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • \u805a\u5408\u51fd\u6570<\/li>\n\n\n\n
                            • \u65e5\u671f\u548c\u65f6\u95f4\u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • IFNULL<\/code> \u548c COALESCE<\/code> \u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • CAST<\/code> \u8868\u8fbe\u5f0f<\/li>\n\n\n\n
                            • \u5b50\u67e5\u8be2\u4f5c\u4e3a\u8868\u8fbe\u5f0f<\/li>\n<\/ul>\n\n\n\n
                              \u901a\u8fc7\u7075\u6d3b\u4f7f\u7528\u8fd9\u4e9b\u8868\u8fbe\u5f0f\uff0c\u53ef\u4ee5\u5728 SQL \u67e5\u8be2\u4e2d\u5b9e\u73b0\u5404\u79cd\u590d\u6742\u7684\u6570\u636e\u5904\u7406\u548c\u8ba1\u7b97\u3002\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
                              \u5728 SQLite \u4e2d\uff0c\u8868\u8fbe\u5f0f\u662f\u901a\u8fc7\u8fd0\u7b97\u7b26\u3001\u5e38\u91cf\u3001\u5217\u540d\u548c\u51fd\u6570\u7ec4\u5408\u8d77\u6765\u7684\u3002\u5b83\u4eec\u5728 SQL \u67e5\u8be2\u4e2d\u7528\u4e8e\u751f\u6210\u6216\u8ba1\u7b97\u4e00\u4e2a […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[76],"tags":[],"class_list":["post-2322","post","type-post","status-publish","format-standard","hentry","category-sqlite"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2322","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=2322"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2322\/revisions"}],"predecessor-version":[{"id":2323,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2322\/revisions\/2323"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=2322"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=2322"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=2322"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}