{"id":70,"date":"2026-08-30T21:04:55","date_gmt":"2026-08-30T13:04:55","guid":{"rendered":"https:\/\/www.233xianyu.top\/?p=70"},"modified":"2026-08-30T21:05:33","modified_gmt":"2026-08-30T13:05:33","slug":"4%e3%80%81%e6%95%b0%e6%8d%ae%e5%ba%93%e7%9a%84%e6%9f%a5%e8%af%a2","status":"publish","type":"post","link":"https:\/\/www.233xianyu.top\/index.php\/2026\/08\/30\/4%e3%80%81%e6%95%b0%e6%8d%ae%e5%ba%93%e7%9a%84%e6%9f%a5%e8%af%a2\/","title":{"rendered":"04\u3001\u6570\u636e\u5e93\u7684\u67e5\u8be2"},"content":{"rendered":"

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group by\u4f8b\u5b50\r\n\r\nselect post,avg(salary) from employee group by post;\r\n\r\n\u53d6\u51fa\u6bcf\u4e2a\u90e8\u95e8\u7684\u5458\u5de5\u6570\r\nselect post,count(id) from employee group by post;\r\n\r\n\u6c42\u7537\u4eba\u6570\u4e0e\u5973\u4eba\u6570\r\nselect sex,count(id) from employee group by sex;\r\n\r\n\u6c42\u5e74\u9f84\u572820\u5c81\u4ee5\u4e0a\u7684\u7537\u4eba\u6570\u4e0e\u5973\u4eba\u6570\r\nselect sex,count(id) from employee where age > 20 group by sex;\r\n\r\n\u6c42\u6bcf\u4e2a\u90e8\u95e820\u5c81\u4ee5\u4e0a\u7684\u4eba\u7684\u5e73\u5747\u85aa\u8d44\r\nselect post,avg(salary) from employee where age > 20 group by post;\r\n\r\n\r\n----------------------------------------\r\nhaving\u4f8b\u5b50\r\n\r\n\u67e5\u51fa\u5e73\u5747\u85aa\u8d44\u572810000\u4ee5\u4e0a\u7684\u90e8\u95e8\r\nselect post,avg(salary) from employee group by post having avg(salary) > 10000;\r\n\r\n\u67e5\u51fa\u90e8\u95e8\u5185\u7537\u5458\u5de5\u5e73\u5747\u5de5\u8d44\u57283000\u4ee5\u4e0a\u7684\u90e8\u95e8\r\nselect post,avg(salary) from employee where sex=\"male\" group by post having avg(salary) > 3000;\r\n\r\n\r\n-----------------------------------------------\r\norder by\r\n\r\nselect * from employee order by age asc;\r\nselect * from employee order by age desc;\r\n\r\n\u67e5\u51fa\u90e8\u95e8\u5185\u7537\u5458\u5de5\u5e73\u5747\u5de5\u8d44\u57283000\u4ee5\u4e0a\u7684\u90e8\u95e8\u4e14\u4ee5\u8fd9\u4e2a\u5e73\u5747\u5de5\u8d44\u6392\u5e8f(\u5347\u5e8f)\r\nselect post,avg(salary) from employee where sex=\"male\" group by post having avg(salary) > 3000 order by avg(salary);\r\n\r\n\r\n----------------------------------------\r\nlimit\r\n\r\n\u53d6\u51fa\u85aa\u8d44\u6700\u9ad8\u7684\u90a3\u4e2a\u4eba\u7684\u4fe1\u606f\r\nselect * from employee order by salary desc limit 1;\r\n\r\n\u4ece0\u5f00\u59cb\u5f80\u540e\u8bfb5\u6761,\u4ee5\u6b64\u7c7b\u63a8\u8bfb\u5230\u7b2c20\u6761\r\nselect * from employee limit 0,5;\r\nselect * from employee limit 5,5;\r\nselect * from employee limit 10,5;\r\nselect * from employee limit 15,5;\r\n\r\n\r\n-----------------------------------\r\n\u591a\u8868\u67e5\u8be2\r\n\u5185\u8fde\u63a5\r\n\r\n\u67e5\u8be2\u6280\u672f\u90e8\u7684\u5458\u5de5\u7684\u59d3\u540d\r\nselect employee.name from employee inner join department on employee.dep_id = department.id where department.name = \"\u6280\u672f\";\r\n\r\n\u67e5\u8be2\u5e73\u5747\u5e74\u9f84\u5927\u4e8e25\u5c81\u7684\u90e8\u95e8\u540d\r\nselect department.name,avg(age) from employee inner join department on employee.dep_id = department.id\r\ngroup by department.name having avg(age) > 25;\r\n\r\n\r\n-----------------------------------------------------\r\n\u5b50\u67e5\u8be2\r\n\r\n\u67e5\u8be2\u51fa\u90a3\u4e9b\u85aa\u8d44\u6bd4\u6240\u6709\u90e8\u95e8\u7684\u5e73\u5747\u85aa\u8d44\u90fd\u9ad8\u7684\u5458\u5de5=\u300b\u85aa\u8d44\u5728\u6240\u6709\u90e8\u95e8\u5e73\u5747\u7ebf\u4ee5\u4e0a\u7684\u72d7\u5e01\u8d44\u672c\u5bb6\r\nselect * from employee where salary > all\r\n(select avg(salary) from employee group by post);\r\n\r\n\u67e5\u8be2\u51fa\u90a3\u4e9b\u85aa\u8d44\u6bd4\u6240\u6709\u90e8\u95e8\u7684\u5e73\u5747\u85aa\u8d44\u90fd\u4f4e\u7684\u5458\u5de5=\u300b\u85aa\u8d44\u5728\u6240\u6709\u90e8\u95e8\u5e73\u5747\u7ebf\u4ee5\u4e0b\u7684\u65e0\u4ea7\u9636\u7ea7\u52b3\u82e6\u5927\u4f17\r\nselect * from employee where salary < all\r\n(select avg(salary) from employee group by post);\r\n\r\n\u67e5\u8be2\u51fa\u90a3\u4e9b\u85aa\u8d44\u6bd4\u4efb\u610f\u4e00\u4e2a\u90e8\u95e8\u7684\u5e73\u5747\u85aa\u8d44\u9ad8\u7684\u5458\u5de5=\u300b\u85aa\u8d44\u5728\u4efb\u4e00\u90e8\u95e8\u5e73\u5747\u7ebf\u4ee5\u4e0a\u7684\u5458\u5de5\r\nselect * from employee where salary > all\r\n(select avg(salary) from employee group by post);\r\n<\/code><\/pre>\n
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