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<!doctype html><html lang=en><head><meta charset=utf-8><meta http-equiv=X-UA-Compatible content="IE=edge,chrome=1"><title>Mysql Common Commands - Frank Wang's Coding World</title><meta name=renderer content="webkit"><meta name=viewport content="width=device-width,initial-scale=1,maximum-scale=1"><meta http-equiv=Cache-Control content="no-transform"><meta http-equiv=Cache-Control content="no-siteapp"><meta name=theme-color content="#f8f5ec"><meta name=msapplication-navbutton-color content="#f8f5ec"><meta name=apple-mobile-web-app-capable content="yes"><meta name=apple-mobile-web-app-status-bar-style content="#f8f5ec"><meta name=author content><meta name=description content="Getting started with MySQL: MySQL statement specifications and common MySQL commands. MySQL statement specifications: keywords and function names are all in uppercase; database names, table names, and field names are all in lowercase; SQL statements must end with a semicolon. Common commands for MySQL: create database, view database, delete database, etc."><meta name=keywords content="MySQL,Statement specification,Common commands"><meta name=generator content="Hugo 0.157.0 with theme even"><link rel=canonical href=http://frankwang0909.github.io/mysql-basic.html><link rel=apple-touch-icon sizes=180x180 href=/apple-touch-icon.png><link rel=icon type=image/png sizes=32x32 href=/favicon-32x32.png><link rel=icon type=image/png sizes=16x16 href=/favicon-16x16.png><link rel=manifest href=/manifest.json><link rel=mask-icon href=/safari-pinned-tab.svg color=#5bbad5><link href=/sass/main.min.af7fd1da18d66c2b017df5b4cae508ef44cfcac3fb4c7c7a327fe4f4f9e28b08.css rel=stylesheet><link href=/lib/fancybox/jquery.fancybox-3.1.20.min.css rel=stylesheet><meta property="og:url" content="http://frankwang0909.github.io/mysql-basic.html"><meta property="og:site_name" content="Frank Wang's Coding World"><meta property="og:title" content="Mysql Common Commands"><meta property="og:description" content="Getting started with MySQL: MySQL statement specifications and common MySQL commands. MySQL statement specifications: keywords and function names are all in uppercase; database names, table names, and field names are all in lowercase; SQL statements must end with a semicolon. Common commands for MySQL: create database, view database, delete database, etc."><meta property="og:locale" content="en_US"><meta property="og:type" content="article"><meta property="article:section" content="post"><meta property="article:published_time" content="2017-06-03T22:38:52+08:00"><meta property="article:modified_time" content="2017-06-03T22:38:52+08:00"><meta property="article:tag" content="MySQL"><meta itemprop=name content="Mysql Common Commands"><meta itemprop=description content="Getting started with MySQL: MySQL statement specifications and common MySQL commands. MySQL statement specifications: keywords and function names are all in uppercase; database names, table names, and field names are all in lowercase; SQL statements must end with a semicolon. Common commands for MySQL: create database, view database, delete database, etc."><meta itemprop=datePublished content="2017-06-03T22:38:52+08:00"><meta itemprop=dateModified content="2017-06-03T22:38:52+08:00"><meta itemprop=wordCount content="262"><meta itemprop=keywords content="MySQL,Statement specification,Common commands"><meta name=twitter:card content="summary"><meta name=twitter:title content="Mysql Common Commands"><meta name=twitter:description content="Getting started with MySQL: MySQL statement specifications and common MySQL commands. MySQL statement specifications: keywords and function names are all in uppercase; database names, table names, and field names are all in lowercase; SQL statements must end with a semicolon. Common commands for MySQL: create database, view database, delete database, etc."><!--[if lte IE 9]><script src=https://cdnjs.cloudflare.com/ajax/libs/classlist/1.1.20170427/classList.min.js></script><![endif]--><!--[if lt IE 9]><script src=https://cdn.jsdelivr.net/npm/html5shiv@3.7.3/dist/html5shiv.min.js></script><script src=https://cdn.jsdelivr.net/npm/respond.js@1.4.2/dest/respond.min.js></script><![endif]--></head><body><div id=mobile-navbar class=mobile-navbar><div class=mobile-header-logo><a href=/en/ class=logo>Frank Wang’s Coding World</a></div><div class=mobile-navbar-icon><span></span>
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<span></span></div></div><nav id=mobile-menu class="mobile-menu slideout-menu"><ul class=mobile-menu-list><a href=/en/><li class=mobile-menu-item>Home</li></a><a href=/en/post/><li class=mobile-menu-item>Archives</li></a><a href=/en/tags/><li class=mobile-menu-item>Tags</li></a><a href=/en/categories/><li class=mobile-menu-item>Categories</li></a><a href=/><li class=mobile-menu-item>中文</li></a></ul></nav><div class=container id=mobile-panel><header id=header class=header><div class=logo-wrapper><a href=/en/ class=logo>Frank Wang’s Coding World</a></div><nav class=site-navbar><ul id=menu class=menu><li class=menu-item><a class=menu-item-link href=/en/>Home</a></li><li class=menu-item><a class=menu-item-link href=/en/post/>Archives</a></li><li class=menu-item><a class=menu-item-link href=/en/tags/>Tags</a></li><li class=menu-item><a class=menu-item-link href=/en/categories/>Categories</a></li><li class=menu-item><a class=menu-item-link href=/>中文</a></li></ul></nav></header><main id=main class=main><div class=content-wrapper><div id=content class=content><article class=post><header class=post-header><h1 class=post-title>Mysql Common Commands</h1><div class=post-meta><span class=post-time>2017-06-03</span><div class=post-category><a href=/en/categories/database/>Database</a></div><span class=more-meta>262 words </span><span class=more-meta>2 mins read</span></div></header><div class=post-toc id=post-toc><h2 class=post-toc-title>Contents</h2><div class="post-toc-content always-active"><nav id=TableOfContents><ul><li><a href=#1-mysql-statement-specifications>1. MySQL statement specifications:</a></li><li><a href=#2-common-mysql-commands>2. Common MySQL commands:</a></li></ul></nav></div></div><div class=post-content><h2 id=1-mysql-statement-specifications>1. MySQL statement specifications:</h2><ol><li><p>Keywords and function names should be in all capital letters;</p></li><li><p>Database names, table names, and field names must all be lowercase;</p></li><li><p>SQL statements must end with a semicolon.</p></li></ol><h2 id=2-common-mysql-commands>2. Common MySQL commands:</h2><ol><li>Display the current database version</li></ol><p>SELECT VERSION();</p><ol start=2><li>Display the current time:</li></ol><p>SELECT NOW();</p><ol start=3><li>Display the current user:</li></ol><p>SELECT USER();</p><ol start=4><li>Create a database:</li></ol><p>The syntax is:</p><p>CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name [DEFAULT] CHARACTER SET [=] charset_name;</p><p>Enter the following statement to create database test2:</p><p>CREATE DATABASE test2;</p><p>If database test2 already exists, an error will be reported:</p><p>ERROR 1007 (HY000): Can&rsquo;t create database &rsquo;test2&rsquo;; database exists</p><p>If you add <code>IF NOT EXISTS</code> when creating the database, no error will be reported when encountering an existing database, but there will be a <code>WARNING</code>.</p><p>CREATE DATABASE IF NOT EXISTS test2;
Query OK, 1 row affected, 1 warning (0.00 sec)</p><p>If you want to see WARNING information, just enter <code>SHOW WARNING;</code>.</p><ol start=4><li>View the database:</li></ol><p>The syntax is:</p><p>SHOW {DATABASES | SCHEMAS} [LIKE &lsquo;pattern&rsquo; | WHERE expr];</p><p>Enter the following statement to view</p><p>SHOW DATABASES;</p><ol start=5><li>Delete the database:</li></ol><p>grammar:</p><p>DROP {DATABASE | SCHEMA} [IF EXISTS] db_name</p><p>If database test2 is entered, enter the following statement to delete the database:</p><p>DROP DATABASE test2;</p><p>If the database test2 that needs to be deleted does not exist, an error will be reported.</p><p>ERROR 1008 (HY000): Can&rsquo;t drop database &rsquo;test2&rsquo;; database doesn&rsquo;t exist</p><p>If <code>IF EXISTS</code> is added when deleting, no error will be reported, but a WARNING:</p><p>DROP DATABASE IF EXISTS test2;
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