{"id":221,"date":"2023-01-05T21:24:23","date_gmt":"2023-01-05T13:24:23","guid":{"rendered":"https:\/\/9iwd.top\/?p=221"},"modified":"2023-01-05T21:24:23","modified_gmt":"2023-01-05T13:24:23","slug":"no9-mysql-%e5%88%86%e7%bb%84%e6%9f%a5%e8%af%a2%ef%bc%88%e9%9d%9e%e5%b8%b8%e9%87%8d%e8%a6%81%ef%bc%9a%e4%ba%94%e9%a2%97%e6%98%9f%ef%bc%89","status":"publish","type":"post","link":"http:\/\/9iwd.top\/?p=221","title":{"rendered":"No9 mysql \u5206\u7ec4\u67e5\u8be2\uff08\u975e\u5e38\u91cd\u8981\uff1a\u4e94\u9897\u661f*****\uff09"},"content":{"rendered":"\n<pre class=\"wp-block-code\"><code>\u4ec0\u4e48\u662f\u5206\u7ec4\u67e5\u8be2\uff1f\n\t\u5728\u5b9e\u9645\u7684\u5e94\u7528\u4e2d\uff0c\u53ef\u80fd\u6709\u8fd9\u6837\u7684\u9700\u6c42\uff0c\u9700\u8981\u5148\u8fdb\u884c\u5206\u7ec4\uff0c\u7136\u540e\u5bf9\u6bcf\u4e00\u7ec4\u7684\u6570\u636e\u8fdb\u884c\u64cd\u4f5c\u3002\n\t\u8fd9\u4e2a\u65f6\u5019\u6211\u4eec\u9700\u8981\u4f7f\u7528\u5206\u7ec4\u67e5\u8be2\uff0c\u600e\u4e48\u8fdb\u884c\u5206\u7ec4\u67e5\u8be2\u5462\uff1f\n\t\tselect\n\t\t\t...\n\t\tfrom\n\t\t\t...\n\t\tgroup by\n\t\t\t...\n\t\t\t\n\t\t\u8ba1\u7b97\u6bcf\u4e2a\u90e8\u95e8\u7684\u5de5\u8d44\u548c\uff1f\n\t\t\u8ba1\u7b97\u6bcf\u4e2a\u5de5\u4f5c\u5c97\u4f4d\u7684\u5e73\u5747\u85aa\u8d44\uff1f\n\t\t\u627e\u51fa\u6bcf\u4e2a\u5de5\u4f5c\u5c97\u4f4d\u7684\u6700\u9ad8\u85aa\u8d44\uff1f\n\t\t....<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>\u5c06\u4e4b\u524d\u7684\u5173\u952e\u5b57\u5168\u90e8\u7ec4\u5408\u5728\u4e00\u8d77\uff0c\u6765\u770b\u4e00\u4e0b\u4ed6\u4eec\u7684\u6267\u884c\u987a\u5e8f\uff1f\n\tselect\n\t\t...\n\tfrom\n\t\t...\n\twhere\n\t\t...\n\tgroup by\n\t\t...\n\torder by\n\t\t...\n\t\n\t\u4ee5\u4e0a\u5173\u952e\u5b57\u7684\u987a\u5e8f\u4e0d\u80fd\u98a0\u5012\uff0c\u9700\u8981\u8bb0\u5fc6\u3002\n\t\u6267\u884c\u987a\u5e8f\u662f\u4ec0\u4e48\uff1f\n\t\t1. from\n\t\t2. where\n\t\t3. group by\n\t\t4. select\n\t\t5. order by\n\t\n\t\u4e3a\u4ec0\u4e48\u5206\u7ec4\u51fd\u6570\u4e0d\u80fd\u76f4\u63a5\u4f7f\u7528\u5728where\u540e\u9762\uff1f\n\t\tselect ename,sal from emp where sal &gt; min(sal);\/\/\u62a5\u9519\u3002\n\t\t\u56e0\u4e3a\u5206\u7ec4\u51fd\u6570\u5728\u4f7f\u7528\u7684\u65f6\u5019\u5fc5\u987b\u5148\u5206\u7ec4\u4e4b\u540e\u624d\u80fd\u4f7f\u7528\u3002\n\t\twhere\u6267\u884c\u7684\u65f6\u5019\uff0c\u8fd8\u6ca1\u6709\u5206\u7ec4\u3002\u6240\u4ee5where\u540e\u9762\u4e0d\u80fd\u51fa\u73b0\u5206\u7ec4\u51fd\u6570\u3002\n\n\t\t\tselect sum(sal) from emp; \n\t\t\t\u8fd9\u4e2a\u6ca1\u6709\u5206\u7ec4\uff0c\u4e3a\u5565sum()\u51fd\u6570\u53ef\u4ee5\u7528\u5462\uff1f\n\t\t\t\u56e0\u4e3aselect\u5728group by\u4e4b\u540e\u6267\u884c\u3002<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>\/*\n\u627e\u51fa\u6bcf\u4e2a\u5de5\u4f5c\u5c97\u4f4d\u7684\u5de5\u8d44\u548c\uff1f\n\u5b9e\u73b0\u601d\u8def\uff1a\u6309\u7167\u5de5\u4f5c\u5c97\u4f4d\u5206\u7ec4\uff0c\u7136\u540e\u5bf9\u5de5\u8d44\u6c42\u548c\u3002\nselect \n\tjob,sum(sal)\nfrom\n\temp\ngroup by\n\tjob;\n*\/\nmysql&gt; select\n    -&gt; job,sum(sal)\n    -&gt; from\n    -&gt; emp\n    -&gt; group by\n    -&gt; job;\n+-----------+----------+\n| job       | sum(sal) |\n+-----------+----------+\n| ANALYST   |  6000.00 |\n| CLERK     |  4150.00 |\n| MANAGER   |  8275.00 |\n| PRESIDENT |  5000.00 |\n| SALESMAN  |  5600.00 |\n+-----------+----------+\n\/*\n\u4ee5\u4e0a\u8fd9\u4e2a\u8bed\u53e5\u7684\u6267\u884c\u987a\u5e8f\uff1f\n\t\u5148\u4eceemp\u8868\u4e2d\u67e5\u8be2\u6570\u636e\u3002\n\t\u6839\u636ejob\u5b57\u6bb5\u8fdb\u884c\u5206\u7ec4\u3002\n\t\u7136\u540e\u5bf9\u6bcf\u4e00\u7ec4\u7684\u6570\u636e\u8fdb\u884csum(sal)\n\n\u91cd\u70b9\u7ed3\u8bba\uff1a\n\t\u5728\u4e00\u6761select\u8bed\u53e5\u5f53\u4e2d\uff0c\u5982\u679c\u6709group by\u8bed\u53e5\u7684\u8bdd\uff0c\n\tselect\u540e\u9762\u53ea\u80fd\u8ddf\uff1a\u53c2\u52a0\u5206\u7ec4\u7684\u5b57\u6bb5\uff0c\u4ee5\u53ca\u5206\u7ec4\u51fd\u6570\u3002\n\t\u5176\u5b83\u7684\u4e00\u5f8b\u4e0d\u80fd\u8ddf\u3002\n*\/<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/\u627e\u51fa\u6bcf\u4e2a\u90e8\u95e8\u7684\u6700\u9ad8\u85aa\u8d44\n\/\/\u5b9e\u73b0\u601d\u8def\u662f\u4ec0\u4e48\uff1f\n\/\/\u6309\u7167\u90e8\u95e8\u7f16\u53f7\u5206\u7ec4\uff0c\u6c42\u6bcf\u4e00\u7ec4\u7684\u6700\u5927\u503c\u3002\n\nmysql&gt; select deptno,max(sal) from emp group by deptno;\n+--------+----------+\n| deptno | max(sal) |\n+--------+----------+\n|     10 |  5000.00 |\n|     20 |  3000.00 |\n|     30 |  2850.00 |\n+--------+----------+<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/\u627e\u51fa\u201c\u6bcf\u4e2a\u90e8\u95e8\uff0c\u4e0d\u540c\u5de5\u4f5c\u5c97\u4f4d\u201d\u7684\u6700\u9ad8\u85aa\u8d44\uff1f\n+--------+-----------+---------+--------+\n| ename  | job       | sal     | deptno |\n+--------+-----------+---------+--------+\n| MILLER | CLERK     | 1300.00 |     10 |\n| KING   | PRESIDENT | 5000.00 |     10 |\n| CLARK  | MANAGER   | 2450.00 |     10 |\n| FORD   | ANALYST   | 3000.00 |     20 |\n| ADAMS  | CLERK     | 1100.00 |     20 |\n| SCOTT  | ANALYST   | 3000.00 |     20 |\n| JONES  | MANAGER   | 2975.00 |     20 |\n| SMITH  | CLERK     |  800.00 |     20 |\n| BLAKE  | MANAGER   | 2850.00 |     30 |\n| MARTIN | SALESMAN  | 1250.00 |     30 |\n| ALLEN  | SALESMAN  | 1600.00 |     30 |\n| TURNER | SALESMAN  | 1500.00 |     30 |\n| WARD   | SALESMAN  | 1250.00 |     30 |\n| JAMES  | CLERK     |  950.00 |     30 |\n+--------+-----------+---------+--------+\n\n\/*\n\u6280\u5de7\uff1a\u4e24\u4e2a\u5b57\u6bb5\u8054\u5408\u62101\u4e2a\u5b57\u6bb5\u770b\u3002\uff08\u4e24\u4e2a\u5b57\u6bb5\u8054\u5408\u5206\u7ec4\uff09\nselect \n\tdeptno, job, max(sal)\nfrom\n\temp\ngroup by\n\tdeptno, job;\n*\/\n\nmysql&gt; select\n    -&gt; deptno, job, max(sal)\n    -&gt; from\n    -&gt; emp\n    -&gt; group by\n    -&gt; deptno, job;\n+--------+-----------+----------+\n| deptno | job       | max(sal) |\n+--------+-----------+----------+\n|     10 | CLERK     |  1300.00 |\n|     10 | MANAGER   |  2450.00 |\n|     10 | PRESIDENT |  5000.00 |\n|     20 | ANALYST   |  3000.00 |\n|     20 | CLERK     |  1100.00 |\n|     20 | MANAGER   |  2975.00 |\n|     30 | CLERK     |   950.00 |\n|     30 | MANAGER   |  2850.00 |\n|     30 | SALESMAN  |  1600.00 |\n+--------+-----------+----------+<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"_links":{"self":[{"href":"http:\/\/9iwd.top\/index.php?rest_route=\/wp\/v2\/posts\/221"}],"collection":[{"href":"http:\/\/9iwd.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/9iwd.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/9iwd.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/9iwd.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=221"}],"version-history":[{"count":4,"href":"http:\/\/9iwd.top\/index.php?rest_route=\/wp\/v2\/posts\/221\/revisions"}],"predecessor-version":[{"id":225,"href":"http:\/\/9iwd.top\/index.php?rest_route=\/wp\/v2\/posts\/221\/revisions\/225"}],"wp:attachment":[{"href":"http:\/\/9iwd.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=221"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/9iwd.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=221"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/9iwd.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}