{"id":303815,"date":"2024-05-20T19:08:29","date_gmt":"2024-05-20T11:08:29","guid":{"rendered":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/303815.html"},"modified":"2024-05-20T19:08:38","modified_gmt":"2024-05-20T11:08:38","slug":"%e6%95%b0%e6%8d%ae%e5%ba%93%e4%b8%ad-sql-%e8%af%ad%e8%a8%80%e7%9a%84%e6%9f%a5%e8%af%a2%e8%af%ad%e5%8f%a5%e5%86%99%e6%b3%95%e6%98%af%e4%bb%80%e4%b9%88","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/303815.html","title":{"rendered":"\u6570\u636e\u5e93\u4e2d SQL \u8bed\u8a00\u7684\u67e5\u8be2\u8bed\u53e5\u5199\u6cd5\u662f\u4ec0\u4e48"},"content":{"rendered":"

\"\u6570\u636e\u5e93\u4e2d<\/p>\n

\u6570\u636e\u5e93\u4e2dSQL\u8bed\u8a00\u7684\u67e5\u8be2\u8bed\u53e5\u5199\u6cd5\u4e3b\u8981\u9075\u5faaSELECT-FROM-WHERE<\/strong>\u7684\u57fa\u672c\u7ed3\u6784\u3002\u8fd9\u4e00\u7ed3\u6784\u4f7f\u5f97\u7528\u6237\u53ef\u4ee5\u7075\u6d3b\u5730\u4ece\u6570\u636e\u5e93\u4e2d\u68c0\u7d22\u6570\u636e\u3002\u67e5\u8be2\u8bed\u53e5<\/strong>\u662f\u6570\u636e\u5e93\u64cd\u4f5c\u4e2d\u6700\u9891\u7e41\u4f7f\u7528\u7684\u4e00\u79cd\u8bed\u53e5\uff0c\u5b83\u5141\u8bb8\u7528\u6237\u6307\u5b9a\u9700\u8981\u68c0\u7d22\u7684\u5b57\u6bb5\uff08\u5217\uff09\u3001\u6570\u636e\u6765\u6e90\uff08\u8868\uff09\u4ee5\u53ca\u68c0\u7d22\u7684\u6761\u4ef6\u3002\u6700\u5e38\u89c1\u7684\u67e5\u8be2\u8bed\u53e5\u5199\u6cd5\u5305\u62ec\uff1a\u9009\u62e9\u7279\u5b9a\u7684\u5217\u3001\u4ece\u591a\u4e2a\u8868\u4e2d\u8fdb\u884c\u9009\u62e9\uff08\u8fde\u63a5\uff09\u3001\u4f7f\u7528\u6761\u4ef6\u8fc7\u6ee4\u7ed3\u679c\u3001\u5bf9\u7ed3\u679c\u8fdb\u884c\u6392\u5e8f<\/strong>\u7b49\u3002\u4ee5\u9009\u62e9\u7279\u5b9a\u7684\u5217\u4e3a\u4f8b\uff0c\u8fd9\u662f\u6700\u76f4\u63a5\u3001\u6700\u7b80\u5355\u7684\u67e5\u8be2\u5f62\u5f0f\uff0c\u901a\u5e38\u4f5c\u4e3aSQL\u5b66\u4e60\u7684\u8d77\u70b9\uff0c\u5b83\u76f4\u63a5\u5f71\u54cd\u6570\u636e\u7684\u68c0\u7d22\u6548\u7387\u548c\u51c6\u786e\u6027\u3002<\/p>\n<\/p>\n

\u4e00\u3001\u57fa\u672c\u67e5\u8be2\u8bed\u53e5\u7ed3\u6784<\/h3>\n<\/p>\n

SQL\u67e5\u8be2\u7684\u6838\u5fc3\u662fSELECT\u8bed\u53e5\uff0c\u5b83\u5141\u8bb8\u7528\u6237\u6307\u5b9a\u4ece\u6570\u636e\u5e93\u8868\u4e2d\u68c0\u7d22\u54ea\u4e9b\u5b57\u6bb5\u3002\u57fa\u672c\u8bed\u6cd5\u542f\u52a8\u4e8eSELECT<\/strong>\u5173\u952e\u5b57\uff0c\u540e\u8ddf\u6240\u9700\u68c0\u7d22\u7684\u5217\u540d\uff0c\u5217\u540d\u4e4b\u95f4\u7528\u9017\u53f7\u9694\u5f00\u3002\u5982\u679c\u9700\u8981\u68c0\u7d22\u6240\u6709\u5217\uff0c\u53ef\u4ee5\u4f7f\u7528\u661f\u53f7(*)\u4f5c\u4e3a\u5feb\u6377\u65b9\u5f0f\u3002<\/p>\n<\/p>\n

FROM<\/strong>\u5b50\u53e5\u6307\u5b9a\u4e86\u5305\u542b\u8fd9\u4e9b\u5217\u7684\u6570\u636e\u8868\u7684\u540d\u5b57\u3002\u5982\u679c\u8981\u5bf9\u68c0\u7d22\u7684\u6570\u636e\u8fdb\u884c\u9650\u5236\uff0c\u53ef\u4ee5\u901a\u8fc7WHERE<\/strong>\u5b50\u53e5\u52a0\u5165\u7279\u5b9a\u7684\u6761\u4ef6\uff0c\u53ea\u8fd4\u56de\u6ee1\u8db3\u8fd9\u4e9b\u6761\u4ef6\u7684\u884c\u3002<\/p>\n<\/p>\n

\u4e8c\u3001\u9009\u62e9\u7279\u5b9a\u7684\u5217<\/h3>\n<\/p>\n

\u5728\u8bb8\u591a\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5e76\u4e0d\u9700\u8981\u4e00\u5f20\u8868\u4e2d\u7684\u6240\u6709\u6570\u636e\uff0c\u800c\u4ec5\u9700\u5176\u4e2d\u51e0\u5217\u3002\u4e3a\u4e86\u63d0\u9ad8\u67e5\u8be2\u6548\u7387\u548c\u51cf\u5c11\u7f51\u7edc\u4f20\u8f93\u91cf\uff0c\u5728SELECT\u8bed\u53e5\u4e2d\u6307\u5b9a\u9700\u8981\u7684\u5217\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u6b64\u65b9\u6cd5\u4e0d\u4ec5\u52a0\u5feb\u4e86\u67e5\u8be2\u901f\u5ea6\uff0c\u8fd8\u8282\u7701\u4e86\u8d44\u6e90\u3002<\/p>\n<\/p>\n

\u4f8b\u5982\uff0c\u4ece\u4e00\u4e2a\u5458\u5de5\u4fe1\u606f\u8868\uff08employees\uff09\u4e2d\u4ec5\u68c0\u7d22\u5458\u5de5\u7684\u59d3\u540d\uff08name\uff09\u548c\u7535\u5b50\u90ae\u4ef6\u5730\u5740\uff08emAI<\/a>l\uff09\uff0c\u53ef\u4ee5\u7f16\u5199\u5982\u4e0bSQL\u8bed\u53e5\uff1a<\/p>\n<\/p>\n

SELECT name, email<\/p>\n
FROM employees;<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u4e09\u3001\u4ece\u591a\u4e2a\u8868\u4e2d\u8fdb\u884c\u9009\u62e9\uff08\u8868\u8fde\u63a5\uff09<\/h3>\n<\/p>\n
\u6570\u636e\u5e93\u8bbe\u8ba1\u901a\u5e38\u9075\u5faa\u89c4\u8303\u5316\u539f\u5219\uff0c\u8fd9\u610f\u5473\u7740\u6570\u636e\u88ab\u5206\u6563\u5728\u591a\u4e2a\u76f8\u5173\u8054\u7684\u8868\u4e2d\u3002\u901a\u8fc7\u8fde\u63a5\uff08JOIN\uff09\u64cd\u4f5c\uff0c\u6211\u4eec\u53ef\u4ee5\u4ece\u591a\u4e2a\u8868\u4e2d\u68c0\u7d22\u6570\u636e\u3002SQL\u63d0\u4f9b\u4e86\u591a\u79cd\u7c7b\u578b\u7684JOIN\uff0c\u5982INNER JOIN\u3001LEFT JOIN\u3001RIGHT JOIN\u7b49\uff0c\u4ee5\u6ee1\u8db3\u4e0d\u540c\u7684\u67e5\u8be2\u9700\u6c42\u3002<\/p>\n<\/p>\n
\u5173\u4e8e\u8868\u8fde\u63a5\u7684\u4e00\u4e2a\u5178\u578b\u4f8b\u5b50\u662f\u4ece\u8ba2\u5355\u8868\uff08orders\uff09\u548c\u5ba2\u6237\u8868\uff08customers\uff09\u4e2d\u68c0\u7d22\u4fe1\u606f\uff0c\u793a\u4f8b\u67e5\u8be2\u8bed\u53e5\u5982\u4e0b\uff1a<\/p>\n<\/p>\n
SELECT orders.order_id, customers.name<\/p>\n
FROM orders<\/p>\n
INNER JOIN customers ON orders.customer_id = customers.id;<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u56db\u3001\u4f7f\u7528\u6761\u4ef6\u8fc7\u6ee4\u7ed3\u679c<\/h3>\n<\/p>\n
\u5728\u8bb8\u591a\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5e0c\u671b\u67e5\u8be2\u7ed3\u679c\u80fd\u6ee1\u8db3\u7279\u5b9a\u7684\u6761\u4ef6\uff0c\u8fd9\u65f6WHERE\u5b50\u53e5\u5c31\u663e\u5f97\u975e\u5e38\u91cd\u8981\u3002\u901a\u8fc7\u5728WHERE\u5b50\u53e5\u4e2d\u6307\u5b9a\u6761\u4ef6\uff0c\u53ef\u4ee5\u4ece\u8868\u4e2d\u7b5b\u9009\u51fa\u6ee1\u8db3\u6761\u4ef6\u7684\u8bb0\u5f55\u3002<\/p>\n<\/p>\n
\u4f8b\u5982\uff0c\u4ece\u5458\u5de5\u8868\u4e2d\u4ec5\u68c0\u7d22\u5de5\u8d44\u9ad8\u4e8e5000\u7684\u5458\u5de5\u4fe1\u606f\uff1a<\/p>\n<\/p>\n
SELECT name, salary<\/p>\n
FROM employees<\/p>\n
WHERE salary > 5000;<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u4e94\u3001\u5bf9\u7ed3\u679c\u8fdb\u884c\u6392\u5e8f<\/h3>\n<\/p>\n
\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u4e0d\u4ec5\u8981\u67e5\u8be2\u6570\u636e\uff0c\u8fd8\u5e0c\u671b\u5c06\u7ed3\u679c\u6309\u7167\u67d0\u4e2a\u7279\u5b9a\u7684\u987a\u5e8f\u8fd4\u56de\uff0c\u8fd9\u53ef\u4ee5\u901a\u8fc7ORDER BY\u5b50\u53e5\u5b9e\u73b0\u3002\u53ef\u4ee5\u6307\u5b9a\u4e00\u4e2a\u6216\u591a\u4e2a\u5217\u4f5c\u4e3a\u6392\u5e8f\u4f9d\u636e\uff0c\u5e76\u53ef\u4ee5\u6307\u5b9a\u5347\u5e8f\uff08ASC\uff09\u6216\u964d\u5e8f\uff08DESC\uff09\u3002<\/p>\n<\/p>\n
\u4f8b\u5982\uff0c\u4ece\u5458\u5de5\u8868\u4e2d\u68c0\u7d22\u6240\u6709\u5458\u5de5\uff0c\u6309\u5de5\u8d44\u5347\u5e8f\u6392\u5217\uff1a<\/p>\n<\/p>\n
SELECT name, salary<\/p>\n
FROM employees<\/p>\n
ORDER BY salary ASC;<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u901a\u8fc7\u5b66\u4e60SQL\u67e5\u8be2\u8bed\u53e5\u7684\u7ed3\u6784\u548c\u5199\u6cd5\uff0c\u6570\u636e\u5206\u6790\u5e08\u548c\u6570\u636e\u5e93\u7ba1\u7406\u5458\u53ef\u4ee5\u6709\u6548\u5730\u4ece\u5927\u91cf\u6570\u636e\u4e2d\u68c0\u7d22\u51fa\u6709\u4ef7\u503c\u7684\u4fe1\u606f\u3002\u638c\u63e1\u8fd9\u4e9b\u57fa\u672c\u7684\u67e5\u8be2\u8bed\u53e5\u5bf9\u4e8e\u4efb\u4f55\u9700\u8981\u4e0e\u6570\u636e\u5e93\u4ea4\u4e92\u7684\u4eba\u6765\u8bf4\u90fd\u662f\u81f3\u5173\u91cd\u8981\u7684\u3002<\/p>\n<\/p>\n
\u76f8\u5173\u95ee\u7b54FAQs\uff1a<\/strong><\/h2>\n
SQL\u8bed\u8a00\u7684\u67e5\u8be2\u8bed\u53e5\u5199\u6cd5\u9700\u8981\u6ce8\u610f\u7684\u51e0\u4e2a\u65b9\u9762\u662f\u54ea\u4e9b\uff1f<\/strong><\/p>\n
    \n
  1. \n
    \u5982\u4f55\u7f16\u5199SELECT\u8bed\u53e5\u4ee5\u68c0\u7d22\u7279\u5b9a\u5217\u7684\u6570\u636e\uff1f<\/strong>
    \n\u53ef\u4ee5\u4f7f\u7528SELECT\u5173\u952e\u5b57\u540e\u8ddf\u8981\u68c0\u7d22\u7684\u5217\u540d\uff0c\u7528\u9017\u53f7\u5206\u9694\uff0c\u4f8b\u5982\uff1aSELECT \u52171, \u52172 FROM \u8868\u540d\u3002\u540c\u65f6\u53ef\u4ee5\u4f7f\u7528\u901a\u914d\u7b26\uff08*\uff09\u68c0\u7d22\u6240\u6709\u5217\u7684\u6570\u636e\u3002<\/p>\n<\/li>\n
  2. \n
    \u5982\u4f55\u7f16\u5199WHERE\u5b50\u53e5\u4ee5\u8fc7\u6ee4\u67e5\u8be2\u7ed3\u679c\uff1f<\/strong>
    \n\u53ef\u4ee5\u4f7f\u7528WHERE\u5b50\u53e5\u6765\u6dfb\u52a0\u6761\u4ef6\u4ee5\u8fc7\u6ee4\u67e5\u8be2\u7ed3\u679c\u3002\u4f8b\u5982\uff0cSELECT \u52171, \u52172 FROM \u8868\u540d WHERE \u6761\u4ef6\u8bed\u53e5\u3002\u6761\u4ef6\u8bed\u53e5\u53ef\u4ee5\u4f7f\u7528\u6bd4\u8f83\u8fd0\u7b97\u7b26\uff08=\uff0c<\uff0c>\uff0c<=\uff0c>=\uff0c<>\uff09\u6216\u903b\u8f91\u8fd0\u7b97\u7b26\uff08AND\uff0cOR\uff0cNOT\uff09\u6765\u5b9a\u4e49\u3002<\/p>\n<\/li>\n
  3. \n
    \u5982\u4f55\u5728\u67e5\u8be2\u7ed3\u679c\u4e2d\u8fdb\u884c\u6392\u5e8f\uff1f<\/strong>
    \n\u4f7f\u7528ORDER BY\u5b50\u53e5\u53ef\u4ee5\u6309\u7167\u6307\u5b9a\u5217\u7684\u5347\u5e8f\u6216\u964d\u5e8f\u5bf9\u7ed3\u679c\u8fdb\u884c\u6392\u5e8f\u3002\u4f8b\u5982\uff0cSELECT \u52171, \u52172 FROM \u8868\u540d ORDER BY \u52171 ASC\uff08\u5347\u5e8f\uff09\u6216SELECT \u52171, \u52172 FROM \u8868\u540d ORDER BY \u52171 DESC\uff08\u964d\u5e8f\uff09\u3002<\/p>\n<\/li>\n
  4. \n
    \u5982\u4f55\u4f7f\u7528GROUP BY\u5b50\u53e5\u5bf9\u67e5\u8be2\u7ed3\u679c\u8fdb\u884c\u5206\u7ec4\uff1f<\/strong>
    \nGROUP BY\u5b50\u53e5\u53ef\u4ee5\u5c06\u67e5\u8be2\u7ed3\u679c\u6309\u7167\u6307\u5b9a\u5217\u7684\u503c\u8fdb\u884c\u5206\u7ec4\u3002\u4f8b\u5982\uff0cSELECT \u52171, \u52172 FROM \u8868\u540d GROUP BY \u52171\u3002\u53ef\u4ee5\u4f7f\u7528HAVING\u5b50\u53e5\u6765\u7b5b\u9009\u5206\u7ec4\u7ed3\u679c\u3002<\/p>\n<\/li>\n
  5. \n
    \u5982\u4f55\u4f7f\u7528JOIN\u6765\u5173\u8054\u591a\u4e2a\u8868\u7684\u6570\u636e\uff1f<\/strong>
    \n\u4f7f\u7528JOIN\u6765\u5c06\u591a\u4e2a\u8868\u7684\u6570\u636e\u8fdb\u884c\u5173\u8054\u3002\u4f8b\u5982\uff0cSELECT \u52171, \u52172 FROM \u88681 JOIN \u88682 ON \u88681.\u5217 = \u88682.\u5217\u3002\u53ef\u4ee5\u4f7f\u7528\u4e0d\u540c\u7c7b\u578b\u7684JOIN\uff08INNER JOIN\uff0cLEFT JOIN\uff0cRIGHT JOIN\uff0cFULL OUTER JOIN\uff09\u6765\u6ee1\u8db3\u4e0d\u540c\u7684\u9700\u6c42\u3002<\/p>\n<\/li>\n
  6. \n
    \u5982\u4f55\u4f7f\u7528\u5b50\u67e5\u8be2\u5728\u67e5\u8be2\u4e2d\u5d4c\u5957\u4e00\u4e2aSELECT\u8bed\u53e5\uff1f<\/strong>
    \n\u5b50\u67e5\u8be2\u662f\u5728\u67e5\u8be2\u8bed\u53e5\u4e2d\u5d4c\u5957\u7684\u53e6\u4e00\u4e2aSELECT\u8bed\u53e5\u3002\u4f8b\u5982\uff0cSELECT \u52171, \u52172 FROM \u8868\u540d WHERE \u52171 IN (SELECT \u52173 FROM \u8868\u540d2 WHERE \u6761\u4ef6)\u3002<\/p>\n<\/li>\n
  7. \n
    \u5982\u4f55\u4f7f\u7528\u805a\u5408\u51fd\u6570\u8ba1\u7b97\u7ed3\u679c\u7684\u603b\u548c\u3001\u5e73\u5747\u503c\u7b49\uff1f<\/strong>
    \n\u805a\u5408\u51fd\u6570\u53ef\u4ee5\u5bf9\u67e5\u8be2\u7ed3\u679c\u8fdb\u884c\u8ba1\u7b97\uff0c\u4f8b\u5982\u6c42\u548c\uff08SUM\uff09\uff0c\u5e73\u5747\u503c\uff08AVG\uff09\uff0c\u6700\u5927\u503c\uff08MAX\uff09\uff0c\u6700\u5c0f\u503c\uff08MIN\uff09\u3002\u4f8b\u5982\uff0cSELECT SUM(\u52171) FROM \u8868\u540d\u3002<\/p>\n<\/li>\n
  8. \n
    \u5982\u4f55\u4f7f\u7528LIMIT\u5b50\u53e5\u9650\u5236\u67e5\u8be2\u7ed3\u679c\u7684\u6570\u91cf\uff1f<\/strong>
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