{"id":2374,"date":"2025-03-04T20:39:50","date_gmt":"2025-03-04T12:39:50","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=2374"},"modified":"2025-03-04T20:39:50","modified_gmt":"2025-03-04T12:39:50","slug":"sqlite-%e5%ad%90%e6%9f%a5%e8%af%a2","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/03\/04\/sqlite-%e5%ad%90%e6%9f%a5%e8%af%a2\/","title":{"rendered":"SQLite\u00a0\u5b50\u67e5\u8be2"},"content":{"rendered":"\n
\n

\u5728 SQLite \u4e2d\uff0c\u5b50\u67e5\u8be2\uff08Subquery\uff09<\/strong> \u662f\u6307\u4e00\u4e2a\u5d4c\u5957\u5728\u53e6\u4e00\u4e2a\u67e5\u8be2\u4e2d\u7684\u67e5\u8be2\u3002\u5b50\u67e5\u8be2\u53ef\u4ee5\u51fa\u73b0\u5728 SQL \u8bed\u53e5\u7684 SELECT<\/code>\u3001INSERT<\/code>\u3001UPDATE<\/code> \u6216 DELETE<\/code> \u8bed\u53e5\u7684\u5404\u4e2a\u90e8\u5206\uff0c\u4f8b\u5982\u5728 WHERE<\/code>\u3001FROM<\/code> \u548c SELECT<\/code> \u5b50\u53e5\u4e2d\u3002<\/p>\n<\/blockquote>\n\n\n\n

\u5b50\u67e5\u8be2\u80fd\u591f\u5e2e\u52a9\u4f60\u4ece\u4e00\u4e2a\u67e5\u8be2\u7684\u7ed3\u679c\u4e2d\u8fdb\u884c\u8ba1\u7b97\u3001\u7b5b\u9009\u6216\u5173\u8054\u6570\u636e\uff0c\u5e76\u4e14\u53ef\u4ee5\u63d0\u4f9b\u66f4\u7075\u6d3b\u3001\u66f4\u5f3a\u5927\u7684\u67e5\u8be2\u65b9\u5f0f\u3002<\/p>\n\n\n\n

1. \u5b50\u67e5\u8be2\u7684\u57fa\u672c\u7ed3\u6784<\/h3>\n\n\n\n

\u4e00\u4e2a\u5b50\u67e5\u8be2\u901a\u5e38\u5199\u5728\u5706\u62ec\u53f7 ()<\/code> \u4e2d\uff0c\u53ef\u4ee5\u4f5c\u4e3a\u4e00\u4e2a\u67e5\u8be2\u7684\u7ec4\u6210\u90e8\u5206\u3002\u4f8b\u5982\uff1a<\/p>\n\n\n\n

SELECT column_name\nFROM table_name\nWHERE column_name = (SELECT column_name FROM other_table WHERE condition);<\/code><\/pre>\n\n\n\n
\u8fd9\u91cc\u7684 SELECT column_name FROM other_table WHERE condition<\/code> \u5c31\u662f\u4e00\u4e2a\u5b50\u67e5\u8be2\u3002<\/p>\n\n\n\n
2. \u5b50\u67e5\u8be2\u7684\u4f7f\u7528\u573a\u666f<\/h3>\n\n\n\n
\u5b50\u67e5\u8be2\u901a\u5e38\u7528\u4e8e\u4ee5\u4e0b\u51e0\u79cd\u60c5\u51b5\uff1a<\/p>\n\n\n\n
    \n
  • \u5728 WHERE<\/code> \u5b50\u53e5\u4e2d\u7b5b\u9009\u6570\u636e\u3002<\/li>\n\n\n\n
  • \u5728 FROM<\/code> \u5b50\u53e5\u4e2d\u4f5c\u4e3a\u865a\u62df\u8868\u4f7f\u7528\u3002<\/li>\n\n\n\n
  • \u5728 SELECT<\/code> \u5b50\u53e5\u4e2d\u4f5c\u4e3a\u8ba1\u7b97\u5217\u3002<\/li>\n\n\n\n
  • \u5728 UPDATE<\/code> \u6216 DELETE<\/code> \u4e2d\u66f4\u65b0\u6216\u5220\u9664\u7b26\u5408\u6761\u4ef6\u7684\u8bb0\u5f55\u3002<\/li>\n<\/ul>\n\n\n\n
    3. \u5b50\u67e5\u8be2\u7684\u7c7b\u578b<\/h3>\n\n\n\n
    3.1 \u6807\u91cf\u5b50\u67e5\u8be2\uff08Scalar Subquery\uff09<\/h4>\n\n\n\n
    \u6807\u91cf\u5b50\u67e5\u8be2\u662f\u4e00\u4e2a\u8fd4\u56de\u5355\u4e2a\u503c\u7684\u5b50\u67e5\u8be2\u3002\u5b83\u5e38\u7528\u5728 SELECT<\/code>\u3001WHERE<\/code> \u6216 HAVING<\/code> \u5b50\u53e5\u4e2d\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u4f7f\u7528\u5b50\u67e5\u8be2\u8fd4\u56de\u5355\u4e00\u503c<\/p>\n\n\n\n
    SELECT first_name, last_name\nFROM employees\nWHERE department_id = (SELECT department_id FROM departments WHERE name = 'HR');<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5b50\u67e5\u8be2 (SELECT department_id FROM departments WHERE name = 'HR')<\/code> \u8fd4\u56de HR<\/code> \u90e8\u95e8\u7684 department_id<\/code>\uff0c\u7136\u540e\u4e3b\u67e5\u8be2\u6839\u636e\u8fd4\u56de\u7684\u503c\u7b5b\u9009\u51fa\u5458\u5de5\u6570\u636e\u3002<\/p>\n\n\n\n
    3.2 \u5217\u5b50\u67e5\u8be2\uff08Column Subquery\uff09<\/h4>\n\n\n\n
    \u5217\u5b50\u67e5\u8be2\u662f\u8fd4\u56de\u4e00\u5217\u6570\u636e\u7684\u5b50\u67e5\u8be2\uff0c\u53ef\u4ee5\u7528\u4e8e IN<\/code>\u3001ANY<\/code>\u3001ALL<\/code> \u7b49\u64cd\u4f5c\u7b26\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u4f7f\u7528 IN<\/code> \u4e0e\u5b50\u67e5\u8be2<\/p>\n\n\n\n
    SELECT first_name, last_name\nFROM employees\nWHERE department_id IN (SELECT department_id FROM departments WHERE location = 'New York');<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5b50\u67e5\u8be2\u8fd4\u56de\u6240\u6709\u5728 “New York” \u5730\u70b9\u7684\u90e8\u95e8\u7684 department_id<\/code>\uff0c\u4e3b\u67e5\u8be2\u901a\u8fc7 IN<\/code> \u64cd\u4f5c\u7b26\u627e\u5230\u5c5e\u4e8e\u8fd9\u4e9b\u90e8\u95e8\u7684\u5458\u5de5\u3002<\/p>\n\n\n\n
    3.3 \u884c\u5b50\u67e5\u8be2\uff08Row Subquery\uff09<\/h4>\n\n\n\n
    \u884c\u5b50\u67e5\u8be2\u662f\u8fd4\u56de\u591a\u5217\u6570\u636e\u7684\u5b50\u67e5\u8be2\u3002\u5b83\u901a\u5e38\u7528\u4e8e WHERE<\/code> \u5b50\u53e5\u4e2d\u7684\u591a\u4e2a\u5217\u6bd4\u8f83\uff0c\u6216\u8005\u7528\u4e8e\u4e0e\u4e3b\u67e5\u8be2\u4e2d\u7684\u591a\u4e2a\u5217\u8fdb\u884c\u6bd4\u8f83\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u4f7f\u7528\u884c\u5b50\u67e5\u8be2<\/p>\n\n\n\n
    SELECT first_name, last_name\nFROM employees\nWHERE (department_id, job_id) = (SELECT department_id, job_id FROM job_history WHERE employee_id = 1001);<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5b50\u67e5\u8be2\u8fd4\u56de\u4e0e\u5458\u5de5 1001<\/code> \u76f8\u540c\u7684 department_id<\/code> \u548c job_id<\/code>\uff0c\u4e3b\u67e5\u8be2\u6839\u636e\u8fd9\u4e9b\u4fe1\u606f\u67e5\u627e\u7b26\u5408\u6761\u4ef6\u7684\u5458\u5de5\u3002<\/p>\n\n\n\n
    3.4 \u5173\u8054\u5b50\u67e5\u8be2\uff08Correlated Subquery\uff09<\/h4>\n\n\n\n
    \u5173\u8054\u5b50\u67e5\u8be2\u662f\u4e00\u4e2a\u4f9d\u8d56\u4e8e\u5916\u90e8\u67e5\u8be2\u7684\u5b50\u67e5\u8be2\uff0c\u5b83\u5728\u5b50\u67e5\u8be2\u4e2d\u5f15\u7528\u4e86\u5916\u90e8\u67e5\u8be2\u7684\u5217\u3002\u6bcf\u4e00\u884c\u5916\u90e8\u67e5\u8be2\u7684\u7ed3\u679c\u90fd\u4f1a\u89e6\u53d1\u4e00\u6b21\u5b50\u67e5\u8be2\u7684\u6267\u884c\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u5173\u8054\u5b50\u67e5\u8be2<\/p>\n\n\n\n
    SELECT first_name, last_name\nFROM employees e\nWHERE salary > (SELECT AVG(salary) FROM employees WHERE department_id = e.department_id);<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5b50\u67e5\u8be2\u8ba1\u7b97\u6bcf\u4e2a\u90e8\u95e8\u7684\u5e73\u5747\u85aa\u6c34\uff0c\u5e76\u4e14\u4e3b\u67e5\u8be2\u901a\u8fc7\u6bd4\u8f83\u5458\u5de5\u7684\u85aa\u6c34\u4e0e\u8be5\u90e8\u95e8\u7684\u5e73\u5747\u85aa\u6c34\u6765\u7b5b\u9009\u6570\u636e\u3002\u6ce8\u610f\u5230\u5b50\u67e5\u8be2\u4e2d\u7684 e.department_id<\/code>\uff0c\u5b83\u5f15\u7528\u4e86\u5916\u90e8\u67e5\u8be2\u4e2d\u7684\u5217\u3002<\/p>\n\n\n\n
    4. \u5b50\u67e5\u8be2\u7684\u5d4c\u5957<\/h3>\n\n\n\n
    \u5b50\u67e5\u8be2\u53ef\u4ee5\u5d4c\u5957\u591a\u5c42\uff0c\u5141\u8bb8\u590d\u6742\u7684\u67e5\u8be2\u3002\u6bcf\u4e00\u5c42\u5b50\u67e5\u8be2\u90fd\u53ef\u4ee5\u72ec\u7acb\u8fd0\u884c\u5e76\u8fd4\u56de\u76f8\u5e94\u7684\u6570\u636e\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u5d4c\u5957\u5b50\u67e5\u8be2<\/p>\n\n\n\n
    SELECT first_name, last_name\nFROM employees\nWHERE department_id = (SELECT department_id FROM departments WHERE name = (SELECT department_name FROM department_names WHERE id = 1));<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u6700\u5185\u5c42\u7684\u5b50\u67e5\u8be2\u9996\u5148\u83b7\u53d6 department_names<\/code> \u8868\u4e2d\u7684 department_name<\/code>\uff0c\u7136\u540e\u4e2d\u95f4\u7684\u5b50\u67e5\u8be2\u4f7f\u7528\u8fd9\u4e2a\u7ed3\u679c\u5728 departments<\/code> \u8868\u4e2d\u627e\u5230 department_id<\/code>\uff0c\u6700\u540e\u4e3b\u67e5\u8be2\u6839\u636e department_id<\/code> \u83b7\u53d6\u76f8\u5e94\u7684\u5458\u5de5\u4fe1\u606f\u3002<\/p>\n\n\n\n
    5. \u5b50\u67e5\u8be2\u4e2d\u7684 EXISTS<\/code> \u548c NOT EXISTS<\/code><\/h3>\n\n\n\n
    EXISTS<\/code> \u548c NOT EXISTS<\/code> \u7528\u4e8e\u5224\u65ad\u5b50\u67e5\u8be2\u662f\u5426\u8fd4\u56de\u7ed3\u679c\u3002EXISTS<\/code> \u7528\u4e8e\u68c0\u67e5\u5b50\u67e5\u8be2\u662f\u5426\u81f3\u5c11\u8fd4\u56de\u4e00\u884c\u6570\u636e\uff0c\u800c NOT EXISTS<\/code> \u7528\u4e8e\u68c0\u67e5\u5b50\u67e5\u8be2\u662f\u5426\u6ca1\u6709\u8fd4\u56de\u4efb\u4f55\u6570\u636e\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u4f7f\u7528 EXISTS<\/code> \u5b50\u67e5\u8be2<\/p>\n\n\n\n
    SELECT first_name, last_name\nFROM employees e\nWHERE EXISTS (SELECT 1 FROM departments d WHERE d.department_id = e.department_id AND d.name = 'HR');<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5b50\u67e5\u8be2\u68c0\u67e5\u662f\u5426\u5b58\u5728\u540d\u4e3a “HR” \u7684\u90e8\u95e8\u3002\u5982\u679c\u5b58\u5728\uff0c\u5219\u8fd4\u56de\u8be5\u90e8\u95e8\u7684\u6240\u6709\u5458\u5de5\u3002<\/p>\n\n\n\n
    6. \u5b50\u67e5\u8be2\u5728 UPDATE<\/code> \u548c DELETE<\/code> \u4e2d\u7684\u4f7f\u7528<\/h3>\n\n\n\n
    \u4f60\u8fd8\u53ef\u4ee5\u5728 UPDATE<\/code> \u548c DELETE<\/code> \u8bed\u53e5\u4e2d\u4f7f\u7528\u5b50\u67e5\u8be2\u6765\u52a8\u6001\u5730\u66f4\u65b0\u6216\u5220\u9664\u6570\u636e\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u4f7f\u7528\u5b50\u67e5\u8be2\u66f4\u65b0\u6570\u636e<\/p>\n\n\n\n
    UPDATE employees\nSET salary = salary * 1.1\nWHERE department_id = (SELECT department_id FROM departments WHERE name = 'HR');<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5b50\u67e5\u8be2\u83b7\u53d6 “HR” \u90e8\u95e8\u7684 department_id<\/code>\uff0c\u7136\u540e\u4e3b\u67e5\u8be2\u5c06\u8be5\u90e8\u95e8\u7684\u6240\u6709\u5458\u5de5\u7684\u85aa\u6c34\u589e\u52a0 10%\u3002<\/p>\n\n\n\n
    \u793a\u4f8b\uff1a<\/strong> \u4f7f\u7528\u5b50\u67e5\u8be2\u5220\u9664\u6570\u636e<\/p>\n\n\n\n
    DELETE FROM employees\nWHERE department_id = (SELECT department_id FROM departments WHERE name = 'HR');<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5b50\u67e5\u8be2\u83b7\u53d6 “HR” \u90e8\u95e8\u7684 department_id<\/code>\uff0c\u7136\u540e\u4e3b\u67e5\u8be2\u5220\u9664\u8be5\u90e8\u95e8\u7684\u6240\u6709\u5458\u5de5\u3002<\/p>\n\n\n\n
    7. \u5b50\u67e5\u8be2\u7684\u4f18\u5316<\/h3>\n\n\n\n
      \n
    • \u6027\u80fd<\/strong>\uff1a\u5b50\u67e5\u8be2\u6709\u65f6\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6027\u80fd\u95ee\u9898\uff0c\u5c24\u5176\u662f\u5f53\u5d4c\u5957\u5c42\u6b21\u8f83\u591a\u65f6\u3002\u901a\u5e38\uff0cJOIN<\/code> \u53ef\u4ee5\u66ff\u4ee3\u67d0\u4e9b\u5b50\u67e5\u8be2\uff0c\u7279\u522b\u662f\u5f53\u4f60\u9700\u8981\u4ece\u591a\u4e2a\u8868\u4e2d\u83b7\u53d6\u6570\u636e\u65f6\u3002<\/li>\n\n\n\n
    • \u7d22\u5f15<\/strong>\uff1a\u5bf9\u4e8e\u5b50\u67e5\u8be2\u4e2d\u7684\u5217\uff0c\u786e\u4fdd\u9002\u5f53\u7684\u7d22\u5f15\u5df2\u521b\u5efa\uff0c\u4ee5\u63d0\u9ad8\u67e5\u8be2\u6027\u80fd\u3002<\/li>\n<\/ul>\n\n\n\n
      \u603b\u7ed3<\/h3>\n\n\n\n
        \n
      • \u5b50\u67e5\u8be2<\/strong>\uff1a\u662f\u5728\u4e00\u4e2a\u67e5\u8be2\u4e2d\u5d4c\u5957\u7684\u67e5\u8be2\uff0c\u53ef\u4ee5\u4f5c\u4e3a\u67e5\u8be2\u7684\u6761\u4ef6\u3001\u8ba1\u7b97\u5217\u6216\u5173\u8054\u6570\u636e\u3002<\/li>\n\n\n\n
      • \u7c7b\u578b<\/strong>\uff1a\u5305\u62ec\u6807\u91cf\u5b50\u67e5\u8be2\u3001\u5217\u5b50\u67e5\u8be2\u3001\u884c\u5b50\u67e5\u8be2\u3001\u5173\u8054\u5b50\u67e5\u8be2\u7b49\u3002<\/li>\n\n\n\n
      • \u4f7f\u7528\u573a\u666f<\/strong>\uff1a\u5e38\u7528\u4e8e WHERE<\/code>\u3001FROM<\/code>\u3001SELECT<\/code> \u5b50\u53e5\uff0c\u4ee5\u53ca UPDATE<\/code>\u3001DELETE<\/code> \u4e2d\u3002<\/li>\n\n\n\n
      • \u4f18\u5316<\/strong>\uff1a\u9700\u8981\u6ce8\u610f\u5b50\u67e5\u8be2\u7684\u6027\u80fd\uff0c\u907f\u514d\u8fc7\u5ea6\u5d4c\u5957\u5e76\u8003\u8651\u4f7f\u7528 JOIN<\/code> \u8fdb\u884c\u4f18\u5316\u3002<\/li>\n<\/ul>\n\n\n\n
        \u901a\u8fc7\u5408\u7406\u4f7f\u7528\u5b50\u67e5\u8be2\uff0c\u53ef\u4ee5\u4f7f\u67e5\u8be2\u66f4\u7b80\u6d01\u3001\u66f4\u5f3a\u5927\uff0c\u5e76\u80fd\u591f\u5904\u7406\u590d\u6742\u7684\u6570\u636e\u5e93\u9700\u6c42\u3002\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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