{"id":737,"date":"2019-05-01T17:54:16","date_gmt":"2019-05-01T09:54:16","guid":{"rendered":"http:\/\/www.eait.co\/?p=737"},"modified":"2019-05-01T17:58:32","modified_gmt":"2019-05-01T09:58:32","slug":"mysql%ef%bc%88%e4%ba%8c%ef%bc%89","status":"publish","type":"post","link":"https:\/\/notes.coremix.net\/?p=737","title":{"rendered":"Mysql\uff08\u4e8c\uff09"},"content":{"rendered":"<div>select * from students where id&lt;5;<\/div>\n<div>\u7b5b\u9009\u51faid\u5c0f\u4e8e5\u7684<\/div>\n<div>select id from student;<\/div>\n<div>\u7b5b\u9009\u51faid\u5b57\u6bb5<\/div>\n<div>select * from student where id is not null;<\/div>\n<div>\u4ece\u8868\u4e2d\u9009\u51faid\u4e0d\u4e3a\u7a7a\u7684\u884c<\/div>\n<div>update student set name = &#8216;moran&#8217; where id = 1;<\/div>\n<div>\u5c06id\u4e3a1\u7684name\u5b57\u6bb5\u8bbe\u7f6e\u4e3amoran\u3002<\/div>\n<div>select * from student where name = &#8216;moran&#8217; and age = 18;<\/div>\n<div>\u5c06\u540d\u5b57\u7b49\u4e8emoran\u5e76\u4e14age\u7b49\u4e8e18\u7684\u884c\u67e5\u627e\u51fa\u6765<\/div>\n<div>\u53ef\u4ee5\u5c06*\u00a0\u6539\u6210name\u00a0age\u00a0\u6765\u53ea\u663e\u793a\u8fd9\u4e24\u4e2a\u5b57\u6bb5\u7684\u503c\u3002<\/div>\n<div>select name age from student where not id = 1;<\/div>\n<div>\u5c06id\u4e0d\u7b49\u4e8e1\u00a0\u7684\u884c\u7684name\u548cage\u5b57\u6bb5\u9009\u62e9\u51fa\u6765<\/div>\n<div>select * from student where order by age [ase];<\/div>\n<div>\u5c06\u9009\u51fa\u7684\u8868\u6309\u5e74\u9f84\u987a\u5e8f\u6392\u5e8f\uff0c\u4e0d\u6539\u53d8\u539f\u8868\u987a\u5e8f\u3002\u9ed8\u8ba4ase\u5347\u5e8f\uff0c\u53ef\u6539\u4e3adesec\u964d\u5e8f<\/div>\n<div>select * from student where limit 2;<\/div>\n<div>\u53ea\u663e\u793a\u67e5\u8be2\u5230\u7684\u524d2\u6761<\/div>\n<div>select * from student limit 2,4;<\/div>\n<div>\u663e\u793a\u7b2c\u4e09\u6761\u7b2c\u56db\u6761\u7b2c\u4e94\u6761\uff08\u7b2c\u4e00\u4e2a\u4e0b\u6807\u4e3a0\uff0c\u5de6\u95ed\u53f3\u95ed\uff09<\/div>\n<div>select * from student order by id\u00a0 limit 3;<\/div>\n<div>\u7528id\u6392\u5e8f\u540e\u518d\u663e\u793a\u524d\u9762\u4e09\u6761\u3002<\/div>\n<div>select *\u00a0from student where id &gt; 2 order by id limit 3;<\/div>\n<div>\u5148\u7b5b\u9009\u51faid\u5927\u4e8e2\u00a0\u7684\u7136\u540e\u518d\u6392\u5e8f\uff0c\u6700\u540e\u663e\u793a\u524d\u9762\u4e09\u6761<\/div>\n<div>select distinct * from student;<\/div>\n<div>\u53bb\u91cd\u67e5\u8be2\uff0c\u5fc5\u987b\u4e24\u884c\u5b8c\u5168\u4e00\u6837\u624d\u53ef\u4ee5\uff0c\u540c\u7406\uff0c\u5982\u679c\u9650\u5236\u5b57\u6bb5\u540d\uff0c\u9700\u8981\u503c\u5b8c\u5168\u4e00\u6837\u3002<\/div>\n<div>select * from student where name like &#8216;s%&#8217;;<\/div>\n<div>\u67e5\u8be2\u5185\u5bb9\uff0c\u540d\u5b57\u4ee5s\u5f00\u5934\u7684\u3002%\u8868\u793a\u540e\u9762\u4e0d\u9650\u6570\u91cf\uff0c\u653e\u5728\u524d\u9762\u7684\u8bdd\u662f\u524d\u9762\u4e0d\u9650\u6570\u91cf<\/div>\n<div>_\u8868\u793a\u5355\u4e2a\u5b57\u7b26\u4e0d\u9650\u5185\u5bb9\u3002<\/div>\n<div>select * from student where id between 2 and 4;<\/div>\n<div>\u663e\u793a2\u52304\u4e4b\u95f4\u7684\uff0c\u5305\u62ec2\u00a0\u548c4 \uff0c\u5de6\u95ed\u53f3\u95ed<\/div>\n<div>select * from student where id in(1,2,3,5);<\/div>\n<div>\u9009\u62e9\u7684\u503c\u5305\u542b\u5728in\u540e\u9762\u7684\u62ec\u53f7\u91cc\u3002<\/div>\n<div>select count(age) from student;<\/div>\n<div>\u7edf\u8ba1\u51fa\u73b0\u7684\u6b21\u6570\uff0cnull\u503c\u4e0d\u7b97\u8fdb\u51fa\u73b0\u7684\u6b21\u6570\u91cc\u9762<\/div>\n<div>\u5176\u4ed6\u805a\u5408\u51fd\u6570\uff1a<\/div>\n<div>\u7edf\u8ba1\u4e2a\u6570\uff1a\u00a0count\uff08column\uff09<\/div>\n<div>\u6c42\u548c\uff1a\u00a0sum\uff08column\uff09<\/div>\n<div>\u6700\u5927\u503c\uff1a\u00a0max\uff08column\uff09<\/div>\n<div>\u5e73\u5747\u503c\uff1a\u00a0avg\uff08column\uff09<\/div>\n<div>\u6700\u5c0f\u503c\uff1a\u00a0min\uff08column\uff09<\/div>\n<div>\u5217\u51fa\u5168\u90e8\u5b57\u6bb5\u503c\uff1a\u00a0group_concat(column)<\/div>\n<div><\/div>\n<div>select grade from students group by\u00a0grade;<\/div>\n<div>\u5217\u51fa\u4e09\u4e2a\u5e74\u7ea7<\/div>\n<div>\u6ce8\u610f\uff1a\u00a0\u5728\u5206\u7ec4\u7684\u60c5\u51b5\u4e0b\uff0c\u53ea\u80fd\u80fd\u591f\u51fa\u73b0\u5206\u7ec4\u5b57\u6bb5\u548c\u805a\u5408\u5b57\u6bb5\uff0c\u5176\u4ed6\u7684\u5b57\u6bb5\u6ca1\u6709\u610f\u4e49\uff0c\u4f1a\u62a5\u9519\u3002<\/div>\n<div><\/div>\n<div>select age, grade from student group by\u00a0age,grade;<\/div>\n<div>\u6839\u636e\u59d3\u540d\u548c\u5e74\u7ea7\u53bb\u5206\u7ec4\u3002<\/div>\n<div><\/div>\n<div>select id from student group by id having id &lt; 5;<\/div>\n<div>\u7b5b\u9009id\u5c0f\u4e8e5<\/div>\n<div>select id from student where id &gt; 2 group id &lt; 49;<\/div>\n<div>\u7b5b\u9009id&gt; 2\u00a0\u5e76\u4e14id&lt; 49\u7684\u5e76\u663e\u793aid\u3002<\/div>\n<div><\/div>\n<div>\u987a\u5e8f\uff1a<\/div>\n<div>\u5148\u6267\u884cwhere\u7136\u540e\u6267\u884c\u805a\u5408\u51fd\u6570\u548c\u522b\u540d\uff0c\u6700\u540e\u6267\u884chaving<\/div>\n<div><\/div>\n<div><\/div>\n<div>select\u00a0count(id) , grade from student group by grade;<\/div>\n<div>\u7edf\u8ba1\u5404\u4e2a\u5e74\u7ea7\u7684\u4eba\u6570\u3002<\/div>\n<div><\/div>\n<div>\u4e0b\u9762\u8fd9\u4e24\u4e2a\u7edf\u8ba1\u5404\u4e2a\u5e74\u7ea7\u5927\u4e8e18\u5c81\u7684\u4eba\u6570\u3002<\/div>\n<div>select count(age)\u00a0 , grade from student where age &gt; 18 group by grade;<\/div>\n<div>\u7b2c\u4e8c\u4e2a\u5148\u627e\u51faage\u5927\u4e8e18\u7684\u7136\u540e\u8fdb\u884c\u5206\u7ec4\uff0c\u6700\u540e\u518d\u7edf\u8ba1age\u7684\u6570\u91cf\u3002<\/div>\n<div>\u7b2c\u4e00\u4e2a\u00a0 \u00a0 \u00a043\u671f\u5e26\u73ed\u8001\u5e08-\u58a8\u67d3\u00a0\u00a023:23:44<\/div>\n<div>\u5148\u805a\u5408\u5206\u7ec4\u00a0\u7136\u540e\u805a\u5408\u51fd\u6570\u00a0\u518dhaving\u7b5b\u9009<\/div>\n<div><\/div>\n<div><\/div>\n<div>select\u00a0count(id) ,grade from student where age&gt; 18 group by grade having grade = &#8216;one&#8217;;<\/div>\n<div>\u7edf\u8ba1\u51fa\u4e00\u5e74\u7ea7\u4eba\u6570\u5927\u4e8e18\u7684\u4eba\u3002<\/div>\n<div>select count(id) ,grade from student group by\u00a0grade having grade = &#8216;one&#8217;;<\/div>\n<div>\u7edf\u8ba1\u51fa\u4e00\u5e74\u7ea7\u7684\u4eba\u6570\u3002<\/div>\n<div><\/div>\n<div>Order by \u6ca1\u52a0<\/div>\n<div>Limit\u6ca1\u52a0<\/div>\n<div>having\u540e\u9762\u52a0\u7684\u6761\u4ef6\u8981\u5728\u805a\u5408\u5206\u7ec4\u91cc\u51fa\u73b0\u7684\u3002<\/div>\n<div><\/div>\n<div>\u8fde\u63a5\u67e5\u8be2\uff1a<\/div>\n<div>\u5185\u8fde\u63a5\uff08inner\u00a0join\uff09<\/div>\n<div>\u65e0\u6761\u4ef6\u5185\u8fde\u63a5\uff1a<\/div>\n<div>\u53c8\u540d\u4ea4\u53c9\u8fde\u63a5\uff08\u7b1b\u5361\u5c14\u8fde\u63a5\uff09<\/div>\n<div>\u7b2c\u4e00\u5f20\u8868\u7684\u6bcf\u4e00\u9879\u4f1a\u548c\u53e6\u4e00\u5f20\u8868\u7684\u6bcf\u4e00\u9879\u4f9d\u6b21\u7ed3\u5408<\/div>\n<div>select * from student [inner] join scoren;<\/div>\n<div>\u6709\u6761\u4ef6\u5185\u8fde\u63a5\uff1a<\/div>\n<div>\u5728\u65e0\u6761\u4ef6\u5185\u8fde\u63a5\u7684\u57fa\u7840\u4e0a\uff0c\u52a0\u4e0a\u4e00\u4e2aon\u5b50\u8bed\u53e5<\/div>\n<div>\u5f53\u8fde\u63a5\u7684\u65f6\u5019\uff0c\u7b5b\u9009\u51fa\u90a3\u4e9b\u6709\u5b9e\u9645\u610f\u4e49\u7684\u8bb0\u5f55\u6765\u8fdb\u884c\u7ec4\u5408<\/div>\n<div>select * from student inner join scoren on dept_id = id;<\/div>\n<div><\/div>\n<div><\/div>\n<div>\u5916\u8fde\u63a5\uff08{left|right} join\uff09<\/div>\n<div>\u5de6\u5916\u94fe\u63a5\uff1a\uff08\u4ee5\u5de6\u8868\u4e3a\u57fa\u51c6\uff09<\/div>\n<div>\u4e24\u5f20\u8868\u505a\u8fde\u63a5\u7684\u65f6\u5019\uff0c\u5728\u8fde\u63a5\u6761\u4ef6\u4e0d\u5339\u914d\u7684\u65f6\u5019<\/div>\n<div>\u7559\u4e0b\u505a\u8868\u7684\u6570\u636e\uff0c\u800c\u53f3\u8868\u7684\u6570\u636e\u4ee52NULL\u586b\u5145<\/div>\n<div>select * from student left join department on dept_id = d_id;<\/div>\n<div><\/div>\n<div>\u53f3\u5916\u8fde\u63a5\uff1a\uff08\u4ee5\u53f3\u8868\u4e3a\u57fa\u51c6\uff09<\/div>\n<div>\u5bf9\u4e24\u5f20\u8868\u505a\u8fde\u63a5\u7684\u65f6\u5019\uff0c\u5728\u8fde\u63a5\u6761\u4ef6\u4e0d\u5339\u914d\u7684\u624b<\/div>\n<div>\u7559\u4e0b\u53f3\u8868\u4e2d\u7684\u6570\u636e\uff0c\u800c\u5de6\u8868\u4e2d\u7684\u6570\u636e\u4ee5NULL\u586b\u5145<\/div>\n<div>select * from student right join department on dept_id = d_id;<\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n<div><\/div>\n","protected":false},"excerpt":{"rendered":"<p>select * from students where id&lt;5; \u7b5b\u9009\u51faid\u5c0f\u4e8e5\u7684 select  [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[],"class_list":["post-737","post","type-post","status-publish","format-standard","hentry","category-python_note"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/notes.coremix.net\/index.php?rest_route=\/wp\/v2\/posts\/737","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/notes.coremix.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/notes.coremix.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/notes.coremix.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/notes.coremix.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=737"}],"version-history":[{"count":2,"href":"https:\/\/notes.coremix.net\/index.php?rest_route=\/wp\/v2\/posts\/737\/revisions"}],"predecessor-version":[{"id":753,"href":"https:\/\/notes.coremix.net\/index.php?rest_route=\/wp\/v2\/posts\/737\/revisions\/753"}],"wp:attachment":[{"href":"https:\/\/notes.coremix.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=737"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/notes.coremix.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=737"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/notes.coremix.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=737"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}