{"id":9142,"date":"2023-01-16T09:21:16","date_gmt":"2023-01-16T01:21:16","guid":{"rendered":"http:\/\/123.57.164.21\/?p=9142"},"modified":"2023-01-16T09:21:16","modified_gmt":"2023-01-16T01:21:16","slug":"%e6%95%b0%e6%8d%ae%e5%ba%93%e7%9a%84%e6%a0%87%e8%af%86%e7%ac%a6%e5%8f%af%e4%bb%a5%e6%9c%89%e5%a4%9a%e9%95%bf","status":"publish","type":"post","link":"https:\/\/92it.top\/?p=9142","title":{"rendered":"\u6570\u636e\u5e93\u7684\u6807\u8bc6\u7b26\u53ef\u4ee5\u6709\u591a\u957f"},"content":{"rendered":"\n<p><strong>\u524d\u8a00<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<p>\u4eca\u5929\u5728\u67e5\u770b\u9879\u76ee\u4ee3\u7801\u65f6\u53d1\u73b0\u6709\u8fd9\u6837\u4e00\u4e2a\u903b\u8f91\uff1a\u5728\u67e5\u8be2\u6570\u636e\u5e93\u65f6\u901a\u8fc7\u4ee3\u7801\u53bb\u62fc\u63a5\u4e00\u4e2aSQL\uff0c\u8fd9\u4e2aSQL\u7684\u67d0\u4e2a\u5b57\u6bb5\u7684\u522b\u540d\u662f\u7531\u591a\u4e2a\u53d8\u91cf\u540d\u62fc\u63a5\u800c\u6210\u7684\uff0c\u4e8e\u662f\u5728\u62fc\u63a5\u8be5\u522b\u540d\u65f6\u7279\u5730\u9650\u5236\u4e86\u5176\u957f\u5ea6\u4e3a30\uff0c\u5982\u679c\u8d85\u8fc730\u5c31\u53ea\u622a\u53d6\u524d30\u4e2a\u5b57\u7b26\u6765\u4f5c\u4e3a\u5217\u522b\u540d\u3002<\/p>\n\n\n\n<p>\u4e00\u65f6\u95f4\u5f88\u597d\u5947\u4e3a\u4ec0\u4e48\u8981\u9650\u5236\u5217\u522b\u540d\u7684\u957f\u5ea6\uff0c\u67e5\u9605\u8fc7\u8d44\u6599\u624d\u660e\u767d\uff0c\u539f\u6765\u6570\u636e\u5e93\u7684\u540d\u5b57\u3001\u8868\u540d\u3001\u8868\u522b\u540d\u3001\u5217\u540d\u3001\u5217\u522b\u540d\u548c\u51fd\u6570\u540d\u7b49\uff0c\u8fd9\u4e9b\u90fd\u5c5e\u4e8e\u6807\u8bc6\u7b26\uff0c\u4e0d\u540c\u6570\u636e\u5e93\u5bf9\u4e8e\u6807\u8bc6\u7b26\u4f1a\u9650\u5b9a\u5404\u79cd\u7684\u957f\u5ea6\u6700\u5927\u503c\u3002<\/p>\n\n\n\n<p><strong>\u5173\u952e\u5b57\u548c\u6807\u8bc6\u7b26<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<p>\u5173\u952e\u5b57\uff1aKey Words\uff0c\u5c31\u662f\u90a3\u4e9b\u5728 SQL \u8bed\u8a00\u91cc\u6709\u56fa\u5b9a\u542b\u4e49\u7684\u5355\u8bcd\u3002\u6bd4\u5982\u5f88\u5e38\u7528\u7684select\u3001update\u3001delete\u7b49\u3002<\/p>\n\n\n\n<p>\u6807\u8bc6\u7b26\uff1aIdentifiers\uff0c\u5c31\u662f\u4e00\u4e2a\u7528\u4e8e\u6807\u8bc6\u7684\u540d\u5b57\uff0c\u6bd4\u5982\u6570\u636e\u5e93\u540d\u3001\u8868\u540d\u3001\u8868\u522b\u540d\u3001\u5217\u540d\u3001\u5217\u522b\u540d\u548c\u51fd\u6570\u540d\u7b49\u3002<br>SQL \u6807\u8bc6\u7b26\u548c\u5173\u952e\u5b57\u5fc5\u987b\u4ee5\u4e00\u4e2a\u5b57\u6bcd\u5f00\u5934 \uff08a-z \u4ee5\u53ca\u5e26\u53ef\u533a\u522b\u6807\u8bb0\u7684\u5b57\u6bcd\u4ee5\u53ca\u975e\u62c9\u4e01\u5b57\u6bcd \uff09\u6216\u4e0b\u5212\u7ebf\u5f00\u5934 \uff08_\uff09\u5f00\u5934\u3002\u6807\u8bc6\u7b26\u548c\u5173\u952e\u5b57\u91cc\u968f\u540e\u7684\u5b57\u7b26\u53ef\u4ee5\u662f\u5b57\u6bcd\uff0c\u6570\u5b57\uff080-9\uff09\uff0c \u6216\u8005\u4e0b\u5212\u7ebf\uff0c\u4f46 SQL \u6807\u51c6\u4e0d\u4f1a\u5b9a\u4e49\u5305\u542b\u6570\u5b57\u6216\u8005\u4ee5\u4e0b\u5212\u7ebf\u5f00\u5934\u6216\u7ed3\u5c3e\u7684\u5173\u952e\u5b57\u3002<\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/123.57.164.21\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-1024x379.png\" alt=\"\" class=\"wp-image-9143\" width=\"590\" height=\"217\" srcset=\"https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-1024x379.png 1024w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-300x111.png 300w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-768x284.png 768w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-1536x568.png 1536w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-830x307.png 830w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-230x85.png 230w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-350x129.png 350w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247-480x178.png 480w, https:\/\/92it.top\/wp-content\/uploads\/2023\/01\/\u56fe\u7247.png 1828w\" sizes=\"(max-width: 590px) 100vw, 590px\" \/><\/figure><\/div>\n\n\n\n<p id=\"postgresql\u4e2d\u7684\u6807\u8bc6\u7b26\"><strong>PostgreSQL\u4e2d\u7684\u6807\u8bc6\u7b26<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<p>PostgreSQL\u6bd4\u8f83\u7279\u6b8a\uff0c\u552f\u72ec\u5b83\u7684\u6807\u8bc6\u7b26\u6700\u5927\u957f\u5ea6\u662f63\u4e2a\u5b57\u7b26\uff0c\u5b98\u65b9\u6587\u6863\u4e2d\u662f\u8fd9\u6837\u63cf\u8ff0\u7684\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">\nThe system uses no more than NAMEDATALEN-1 bytes of an identifier; longer names can be written in commands, but they will be truncated. By default, NAMEDATALEN is 64 so the maximum identifier length is 63 bytes. If this limit is problematic, it can be raised by changing the NAMEDATALEN constant in src\/include\/pg_config_manual.h.\n\nKey words and unquoted identifiers are case insensitive.\n<\/pre>\n\n\n\n<p>\u7b80\u5355\u6765\u8bf4\uff0cPostgreSQL\u4f7f\u7528<code>NAMEDATALEN - 1<\/code>\u7684\u503c\u6765\u9650\u5b9a\u6807\u8bc6\u7b26\u7684\u6700\u5927\u957f\u5ea6\uff0cNAMEDATALEN\u9ed8\u8ba4\u662f64\uff0c\u53ef\u4ee5\u5728PosrgreSQL\u7684\u5b89\u88c5\u76ee\u5f55\u4e0b\u7684<code>include\/pg_config_manual.h<\/code>\u53bb\u4fee\u6539\u5176\u503c\uff0c\u5728\u8be5shell\u6587\u4ef6\u4e2d\u5176\u6ce8\u91ca\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/*\n * Maximum length for identifiers (e.g. table names, column names,\n * function names).  Names actually are limited to one less byte than this,\n * because the length must include a trailing zero byte.\n *\n * Changing this requires an initdb.\n *\/\n#define NAMEDATALEN 64\n<\/pre>\n\n\n\n<p><strong>PostgreSQL\u5173\u4e8e\u6807\u8bc6\u7b26\u7b80\u5355\u7684\u4f8b\u5b50<\/strong><\/p>\n\n\n\n<p>\u5982\u679c\u6211\u4eec\u628a\u6807\u8bc6\u7b26\u547d\u540d\u8d85\u8fc7\u4e86\u6700\u5927\u957f\u5ea6\uff0c\u90a3\u4e48\u4f1a\u88ab\u81ea\u52a8\u622a\u53d6\u6389\u8d85\u51fa\u7684\u90e8\u5206\uff0c\u53ea\u7559\u4e0b\u6700\u5927\u957f\u5ea6\u7684\u6807\u8bc6\u7b26\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">alter table tb_student add \"\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\" varchar(400);\n<\/pre>\n\n\n\n<p>\u5982\u4e0aSQL\uff0c\u7531\u4e8e\u6570\u636e\u5e93\u4f7f\u7528\u7684\u662fUTF-8\u7f16\u7801\uff0c\u4e00\u4e2a\u4e2d\u6587\u5bf9\u5e943\u4e2a\u5b57\u7b26\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u6807\u8bc6\u7b26\u6700\u591a\u53ea\u80fd\u670921\u4e2a\u4e2d\u6587\u3002\u4e0a\u8ff0SQL\u6267\u884c\u6210\u529f\u540e\uff0c<code>tb_student<\/code>\u591a\u51fa\u6765\u4e00\u4e2a\u65b0\u7684\u5b57\u6bb5<code>\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8\u54c8<\/code>\uff0c\u6b63\u597d\u53ea\u670921\u4e2a\u5b57\u7b26\uff0c\u591a\u51fa\u6765\u7684\u5b57\u7b26\u88ab\u4e22\u5f03\u4e86\u3002<\/p>\n\n\n\n<p>\u53e6\u5916\uff0c\u6807\u8bc6\u7b26\u662f\u4e0d\u533a\u5206\u5927\u5c0f\u5199\u7684\uff0c\u4f46\u662f<strong>\u5982\u679c\u7528\u53cc\u5f15\u53f7\u628a\u6807\u8bc6\u7b26\u5305\u62ec\u8d77\u6765<\/strong>\uff0c\u8fd9\u65f6\u5019\u5c31\u4f1a\u533a\u5206\u5927\u5c0f\u5199\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u524d\u8a00 \u4eca\u5929\u5728\u67e5\u770b\u9879\u76ee\u4ee3\u7801\u65f6\u53d1\u73b0\u6709\u8fd9\u6837\u4e00\u4e2a\u903b\u8f91\uff1a\u5728\u67e5\u8be2\u6570\u636e\u5e93\u65f6\u901a\u8fc7\u4ee3\u7801\u53bb\u62fc\u63a5\u4e00\u4e2aSQL\uff0c\u8fd9\u4e2aSQL\u7684\u67d0\u4e2a\u5b57\u6bb5\u7684\u522b [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[],"_links":{"self":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/9142"}],"collection":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=9142"}],"version-history":[{"count":2,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/9142\/revisions"}],"predecessor-version":[{"id":9145,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/9142\/revisions\/9145"}],"wp:attachment":[{"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=9142"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=9142"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=9142"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}