{"id":2562,"date":"2020-12-04T10:36:36","date_gmt":"2020-12-04T02:36:36","guid":{"rendered":"http:\/\/127.0.0.2\/?p=2562"},"modified":"2020-12-04T10:39:51","modified_gmt":"2020-12-04T02:39:51","slug":"2020javaweb%e6%95%99%e7%a8%8b%e4%b9%8bmysql%e4%b9%a0%e9%a2%98%e9%9b%86%e5%90%88","status":"publish","type":"post","link":"https:\/\/www.9713job.com\/?p=2562","title":{"rendered":"2020javaweb\u6559\u7a0b\u4e4bmysql\u4e60\u9898\u96c6\u5408"},"content":{"rendered":"

2020javaweb\u6559\u7a0b\u4e4bmysql\u4e60\u9898\u96c6\u5408<\/h3>\n

\u56de\u987e\u77e5\u8bc6<\/strong><\/span><\/h2>\n

\u7b80\u5355\u67e5\u8be2\uff1aselect*from \u8868\u540d;
\n\u67e5\u8be2\u6307\u5b9a\u5217\uff1aselect sname,score from \u8868\u540d;<\/p>\n

\u6761\u4ef6\u67e5\u8be2\uff1a<\/strong><\/span><\/p>\n

\u6bd4\u8f83\u8fd0\u7b97\u7b26\uff1a<\/p>\n

\u67e5\u8be2\u6027\u522b\u4e3a\u5973\uff0c\u5e76\u4e14\u5e74\u9f84\u5c0f\u4e8e50\u7684\u8bb0\u5f55\uff1a<\/span>
\nselect*from \u8868\u540d where sex=’\u5973’ and age<50;<\/p>\n

\u67e5\u8be2\u5b66\u53f7\u4e3aS_1001\uff0c\u6216\u8005\u59d3\u540d\u4e3aliSi\u7684\u8bb0\u5f55<\/span>
\nselect*from \u8868\u540d wher sid=’S_1001′ or sname=’lisi’;<\/p>\n

\u67e5\u8be2\u5b66\u53f7\u4e3aS _ 1001 \uff0cS _ 1002\uff0cS _ 1003\u7684\u8bb0\u5f55 IN(set)<\/span>
\nselect*from \u8868\u540d where sid=’S_1001′ or sid=’S_1002′ or sid=’S_1003′;
\n\u6216\u8005\uff1a
\nselect*from \u8868\u540d where sid in(‘S_1001′,’S_1002′,’S_1003’);<\/p>\n

\u67e5\u8be2\u5b66\u53f7\u4e0d\u662fS_1001\uff0cS_1002\uff0cS_1003\u7684\u8bb0\u5f55<\/span>
\nselect*from \u8868\u540d where sid not in(‘S_1001′,’S_1002′,’S_1003’);
\n<\/p>\n

\u67e5\u8be2\u5e74\u9f84\u4e3anull\u7684\u8bb0\u5f55<\/span>
\nselect*from \u8868\u540d where age is null;<\/p>\n

\u67e5\u8be2\u5e74\u9f84\u572820\u523040\u4e4b\u95f4\u7684\u5b66\u751f\u8bb0\u5f55<\/span>
\nselect*from \u8868\u540d wher age between 20 and 40;<\/p>\n

\u67e5\u8be2\u6027\u522b\u975e\u7537\u7684\u5b66\u751f\u8bb0\u5f55<\/span>
\nselect*from \u8868\u540d where sex!=’\u7537’;
\nselect*from \u8868\u540d where not sex=’\u7537’;<\/p>\n

\u6392\u5e8f\uff1adesc\u964d\u5e8f\uff0casc\u5347\u5e8f<\/span><\/p>\n

\u5b57\u6bb5\u63a7\u5236\u67e5\u8be2\uff1a<\/span><\/h2>\n

\u53bb\u91cd\uff1adistinct<\/span>
\nselect distinct sname from \u8868\u540d;<\/p>\n

\u67e5\u770b\u96c7\u5458\u7684\u6708\u85aa\u4e0e\u4f63\u91d1\u4e4b\u548c<\/span>
\nselect *,concat(sname,’#’,score) from \u8868\u540d;<\/p>\n

\u5c06null\u503c\u8f6c\u6362\u4e3a0\u8fd0\u7b97<\/span>
\nselect *,salary+ifnull(comm,0) from \u8868\u540d;<\/p>\n

\u7ed9\u5217\u540d\u6dfb\u52a0\u522b\u540d(\u53ef\u7701\u7565 as \u5173\u952e\u5b57)<\/span>
\nselect sname,km,ifnull(score,0) test from score;<\/p>\n

\u67e5\u8be2\u6240\u6709\u96c7\u5458\uff0c\u6309\u6708\u85aa\u964d\u5e8f\u6392\u5e8f\uff0c\u5982\u679c\u6708\u85aa\u76f8\u540c\u65f6\uff0c\u6309\u7f16\u53f7\u5347\u5e8f\u6392\u5e8f<\/span>
\nselect*from emp order by\u00a0 sal desc,empno asc;<\/p>\n

\u5206\u7ec4\u67e5\u8be2<\/span><\/h3>\n

\u67e5\u8be2\u5de5\u8d44\u603b\u548c\u5927\u4e8e9000\u7684\u90e8\u95e8\u7f16\u53f7\u4ee5\u53ca\u5de5\u8d44\u548c<\/span>
\nselect depno,sum(sal) from emp group by depno having sum(sal)>9000<\/p>\n

having\u4e0ewhere\u533a\u522b<\/strong><\/span><\/h3>\n

1.having\u662f\u5728\u5206\u7ec4\u540e\u5bf9\u6570\u636e\u8fdb\u884c\u8fc7\u6ee4\uff0cwhere\u662f\u5728\u5206\u7ec4\u524d\u5bf9\u6570\u636e\u8fdb\u884c\u8fc7\u6ee4\u3002
\n2.having\u540e\u9762\u53ef\u4ee5\u4f7f\u7528\u805a\u5408\u51fd\u6570\uff0cwhere\u540e\u9762\u4e0d\u53ef\u4ee5\u4f7f\u7528\u805a\u5408
\n3.where\u662f\u5bf9\u5206\u7ec4\u524d\u8bb0\u5f55\u7684\u6761\u4ef6\uff0c\u5982\u679c\u67d0\u884c\u8bb0\u5f55\u6ca1\u6709\u6ee1\u8db3where\u5b50\u53e5\u7684\u6761\u4ef6\uff0c\u90a3\u4e48\u8fd9\u884c\u8bb0\u5f55\u4e0d\u4f1a\u53c2\u52a0\u5206\u7ec4\uff1b
\n\u800chaving\u662f\u5bf9\u5206\u7ec4\u540e\u6570\u636e\u548c\u7ea6\u675f<\/p>\n

\u603b\u7ed3\u67e5\u8be2<\/span><\/h2>\n

\u67e5\u8be2\u8bed\u53e5\u4e66\u5199\u987a\u5e8f\uff1a
\nselect \u5217 from \u8868\u540d where–>group by \u5206\u7ec4\u540d–>having–>order by\u6392\u5e8f–>limit \u9650\u5236<\/span><\/p>\n

\u67e5\u8be2\u8bed\u53e5\u6267\u884c\u987a\u5e8f\uff1a
\nfrom \u8868\u540d where–>group by–>having–select–>order by–>limit<\/span><\/p>\n

 <\/p>\n

\u8bfe\u540e\u4e60\u9898\uff1a<\/p>\n

\u67e5\u8be2\u4e24\u95e8\u53ca\u4e24\u95e8\u4ee5\u4e0a\u4e0d\u53ca\u683c\u7684\u5b66\u751f\u59d3\u540d
\nselect sname from stu group by sname having sum(score<60)>=2<\/p>\n

\u67e5\u8be2\u5b66\u751f\u5e73\u5747\u5206
\nselect avg(score)from stu group by sname<\/p>\n

\u67e5\u8be2\u59d3\u540d\u662f\u5f20\u4e09\u7684\u5b66\u751f\u6210\u7ee9
\nselect sname,km,score from \u8868\u540d where sname=’\u5f20\u4e09’;<\/p>\n

\u5c06\u5b66\u751f\u4fe1\u606f\u6309\u7167\u5206\u6570\u5012\u5e8f
\nselect*from \u8868\u540d order by score desc<\/p>\n

\u83b7\u53d6\u5b66\u751f\u4fe1\u606f\u4e2d \u5206\u6570\u6700\u4f4e\u7684\u5b66\u751f\u59d3\u540d\u548c\u5206\u6570\u6700\u9ad8\u7684\u5b66\u751f\u59d3\u540d
\nselect sname,score from \u8868\u540d where score=(select max(score) from \u8868\u540d)
\nor
\nscore=(select min(score) from \u8868\u540d)<\/p>\n

\u67e5\u8be2\u4e24\u95e8\u53ca\u4e24\u95e8\u4ee5\u4e0a\u4e0d\u53ca\u683c\u540c\u5b66\u7684\u5e73\u5747\u5206\u3002
\nselect sname,sum(score<60) gk,avg(score) pj from \u8868\u540d group by sname having gk>=2;<\/p>\n","protected":false},"excerpt":{"rendered":"

2020javaweb\u6559\u7a0b\u4e4bmysql\u4e60\u9898\u96c6\u5408 \u56de\u987e\u77e5\u8bc6 \u7b80\u5355\u67e5\u8be2\uff1aselect*from \u8868\u540d; \u67e5\u8be2\u6307\u5b9a\u5217 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-2562","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/www.9713job.com\/index.php?rest_route=\/wp\/v2\/posts\/2562","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.9713job.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.9713job.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.9713job.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.9713job.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2562"}],"version-history":[{"count":4,"href":"https:\/\/www.9713job.com\/index.php?rest_route=\/wp\/v2\/posts\/2562\/revisions"}],"predecessor-version":[{"id":2566,"href":"https:\/\/www.9713job.com\/index.php?rest_route=\/wp\/v2\/posts\/2562\/revisions\/2566"}],"wp:attachment":[{"href":"https:\/\/www.9713job.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2562"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.9713job.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2562"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.9713job.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2562"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}