{"id":854,"date":"2025-02-18T18:30:25","date_gmt":"2025-02-18T10:30:25","guid":{"rendered":"https:\/\/eve2333.top\/?p=854"},"modified":"2025-02-18T18:30:25","modified_gmt":"2025-02-18T10:30:25","slug":"mysql%e6%95%b0%e6%8d%ae%e5%ba%93%e5%85%a5%e9%97%a8%e5%88%b0%e5%a4%a7%e8%9b%87%e5%b0%9a%e7%a1%85%e8%b0%b7%e5%ae%8b%e7%ba%a2%e5%ba%b7%e8%80%81%e5%b8%88%e7%ac%94%e8%ae%b0-%e5%9f%ba%e7%a1%80%e7%af%87-pa-7","status":"publish","type":"post","link":"https:\/\/eve2333.top\/?p=854","title":{"rendered":"MySQL\u6570\u636e\u5e93\u5165\u95e8\u5230\u5927\u86c7\u5c1a\u7845\u8c37\u5b8b\u7ea2\u5eb7\u8001\u5e08\u7b14\u8bb0 \u57fa\u7840\u7bc7 part 10"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">&nbsp;&nbsp;\u7b2c10\u7ae0_\u521b\u5efa\u548c\u7ba1\u7406\u8868<\/h1>\n\n\n\n<p>DDL\uff1a\u6570\u636e\u5b9a\u4e49\u8bed\u8a00\u3002CREATE&nbsp; &nbsp;\\ALTER\\&nbsp; &nbsp;DROP&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \\RENAME&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; TRUNCATE<br>DML\uff1a\u6570\u636e\u64cd\u4f5c\u8bed\u8a00\u3002INSERT&nbsp; &nbsp;\\DELETE&nbsp; &nbsp; \\UPDATE&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \\SELECT\uff08\u91cd\u4e2d\u4e4b\u91cd\uff09<br>DCL\uff1a\u6570\u636e\u63a7\u5236\u8bed\u8a00\u3002COMMIT&nbsp; &nbsp;\\ROLLBACK&nbsp; &nbsp; SAVEPOINT&nbsp; &nbsp; \\GRANT&nbsp; &nbsp; &nbsp;\\REVOKE<\/p>\n\n\n\n<p>\u524d\u9762\u8bb2\u7684\u90fd\u662fDML ,\u5373\u6570\u636e\u64cd\u4f5c\u8bed\u8a00,\u73b0\u5728\u8bb2\u4e00\u8bb2DDL .&nbsp;<\/p>\n\n\n\n<p>\u5b58\u50a8\u6570\u636e\u662f\u5904\u7406\u6570\u636e\u7684\u7b2c\u4e00\u6b65\u3002\u53ea\u6709\u6b63\u786e\u5730\u628a\u6570\u636e\u5b58\u50a8\u8d77\u6765\uff0c\u6211\u4eec\u624d\u80fd\u8fdb\u884c\u6709\u6548\u7684\u5904\u7406\u548c\u5206\u6790\u3002\u5426\u5219\uff0c\u53ea \u80fd\u662f\u4e00\u56e2\u4e71\u9ebb\uff0c\u65e0\u4ece\u4e0b\u624b\u3002 \u90a3\u4e48\uff0c\u600e\u6837\u624d\u80fd\u628a\u7528\u6237\u5404\u79cd\u7ecf\u8425\u76f8\u5173\u7684\u3001\u7eb7\u7e41\u590d\u6742\u7684\u6570\u636e\uff0c\u6709\u5e8f\u3001\u9ad8\u6548\u5730\u5b58\u50a8\u8d77\u6765\u5462\uff1f \u5728 MySQL \u4e2d\uff0c \u4e00\u4e2a\u5b8c\u6574\u7684\u6570\u636e\u5b58\u50a8\u8fc7\u7a0b\u603b\u5171\u6709 4 \u6b65\uff0c\u5206\u522b\u662f\u521b\u5efa\u6570\u636e\u5e93\u3001\u786e\u8ba4\u5b57\u6bb5\u3001\u521b\u5efa\u6570\u636e\u8868\u3001\u63d2\u5165\u6570\u636e\u3002<img loading=\"lazy\" decoding=\"async\" height=\"136\" width=\"840\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/59e3fb99a17e4bdcbf78b063df837aa7.png\" alt=\"\"><\/p>\n\n\n\n<p>\u6807\u8bc6\u7b26\u547d\u540d\u89c4\u5219&nbsp;<strong>\u770b\u770b\u5c31\u597d<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u6570\u636e\u5e93\u540d\u3001\u8868\u540d\u4e0d\u5f97\u8d85\u8fc730\u4e2a\u5b57\u7b26\uff0c\u53d8\u91cf\u540d\u9650\u5236\u4e3a29\u4e2a<\/li>\n\n\n\n<li>\u5fc5\u987b\u53ea\u80fd\u5305\u542b A\u2013Z, a\u2013z, 0\u20139, _\u517163\u4e2a\u5b57\u7b26<\/li>\n\n\n\n<li>\u6570\u636e\u5e93\u540d\u3001\u8868\u540d\u3001\u5b57\u6bb5\u540d\u7b49\u5bf9\u8c61\u540d\u4e2d\u95f4\u4e0d\u8981\u5305\u542b\u7a7a\u683c<\/li>\n\n\n\n<li>\u4e00\u4e2aMySQL\u8f6f\u4ef6\u4e2d\uff0c\u6570\u636e\u5e93\u4e0d\u80fd\u540c\u540d\uff1b\u540c\u4e00\u4e2a\u5e93\u4e2d\uff0c\u8868\u4e0d\u80fd\u91cd\u540d\uff1b\u540c\u4e00\u4e2a\u8868\u4e2d\uff0c\u5b57\u6bb5\u4e0d\u80fd\u91cd\u540d<\/li>\n\n\n\n<li>\u5fc5\u987b\u4fdd\u8bc1\u4f60\u7684\u5b57\u6bb5\u6ca1\u6709\u548c\u4fdd\u7559\u5b57\u3001\u6570\u636e\u5e93\u7cfb\u7edf\u6216\u5e38\u7528\u65b9\u6cd5\u51b2\u7a81\u3002\u5982\u679c\u575a\u6301\u4f7f\u7528\uff0c\u8bf7\u5728SQL\u8bed\u53e5\u4e2d\u4f7f \u7528`\uff08\u7740\u91cd\u53f7\uff09\u5f15\u8d77\u6765<\/li>\n\n\n\n<li>\u4fdd\u6301\u5b57\u6bb5\u540d\u548c\u7c7b\u578b\u7684\u4e00\u81f4\u6027\uff1a\u5728\u547d\u540d\u5b57\u6bb5\u5e76\u4e3a\u5176\u6307\u5b9a\u6570\u636e\u7c7b\u578b\u7684\u65f6\u5019\u4e00\u5b9a\u8981\u4fdd\u8bc1\u4e00\u81f4\u6027\uff0c\u5047\u5982\u6570\u636e \u7c7b\u578b\u5728\u4e00\u4e2a\u8868\u91cc\u662f\u6574\u6570\uff0c\u90a3\u5728\u53e6\u4e00\u4e2a\u8868\u91cc\u53ef\u5c31\u522b\u53d8\u6210\u5b57\u7b26\u578b\u4e86<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">2. \u521b\u5efa\u548c\u7ba1\u7406\u6570\u636e\u5e93&nbsp;<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u65b9\u5f0f1\uff1a\u521b\u5efa\u6570\u636e\u5e93 CREATE DATABASE \u6570\u636e\u5e93\u540d;<\/li>\n\n\n\n<li>\u65b9\u5f0f2\uff1a\u521b\u5efa\u6570\u636e\u5e93\u5e76\u6307\u5b9a\u5b57\u7b26\u96c6 CREATE DATABASE \u6570\u636e\u5e93\u540d CHARACTER SET \u5b57\u7b26\u96c6;<\/li>\n\n\n\n<li>\u65b9\u5f0f3\uff1a\u5224\u65ad\u6570\u636e\u5e93\u662f\u5426\u5df2\u7ecf\u5b58\u5728\uff0c\u4e0d\u5b58\u5728\u5219\u521b\u5efa\u6570\u636e\u5e93\uff08 CREATE DATABASE IF NOT EXISTS \u6570\u636e\u5e93\u540d; \u63a8\u8350\uff09<\/li>\n<\/ol>\n\n\n\n<p>\u5982\u679cMySQL\u4e2d\u5df2\u7ecf\u5b58\u5728\u76f8\u5173\u7684\u6570\u636e\u5e93\uff0c\u5219\u5ffd\u7565\u521b\u5efa\u8bed\u53e5\uff0c\u4e0d\u518d\u521b\u5efa\u6570\u636e\u5e93\u3002 \u6ce8\u610f\uff1a<strong>DATABASE \u4e0d\u80fd\u6539\u540d\u3002\u4e00\u4e9b\u53ef\u89c6\u5316\u5de5\u5177\u53ef\u4ee5\u6539\u540d\uff0c\u5b83\u662f\u5efa\u65b0\u5e93\uff0c\u628a\u6240\u6709\u8868\u590d\u5236\u5230\u65b0\u5e93\uff0c\u518d\u5220\u65e7\u5e93\u5b8c\u6210\u7684\u3002<\/strong><\/p>\n\n\n\n<p>&nbsp;\u9996\u5148\u4f60\u5f97\u6709\u4e00\u4e2a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>CREATE DATABASE mytest1;\nSHOW DATABASES;\n\n\n\u4f1a\u51fa\u73b0\u4e00\u4e2a\u5f88\u957f\u7684\u680f,\u53eb\u505a\"create database\"\u91cc\u9762\u9610\u8ff0\u7684\u6570\u636e\u5e93\u4f7f\u7528\u4e86\u4ec0\u4e48\u6027\u8d28\u683c\u5f0f<\/code><\/pre>\n\n\n\n<p>\u9ed8\u8ba4\u7684\u5b57\u7b26\u96c6\u662fcharacter_set_server\u8fd9\u4e2a\u53c2\u6570\u51b3\u5b9a\u7684.&nbsp; character_set_database\u8fd9\u4e2a\u53c2\u6570\u5728\u4e0d\u540c\u7684\u5ba2\u6237\u7aef\u8f6f\u4ef6\u8dd1\u51fa\u6765\u7684\u7ed3\u679c\u662f\u4e0d\u4e00\u81f4\u7684\uff0c\u4f46\u662fcharacter_set_server\u662f\u4e00\u81f4\u7684<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\u65b9\u5f0f2\uff1a\u8bed\u53e5\u663e\u5f0f\u6307\u5b9a\u6570\u636e\u5e93\u7684\u5b57\u7b26\u96c6\u4e3a gbk\nCREATE DATABASE mytest2 CHARACTER SET 'gbk';\nSHOW CREATE DATABASE mytest2;\n\n\n\u65b9\u5f0f3 (\u63a8\u8350)\uff1a\u5982\u679c\u6570\u636e\u5e93\u5df2\u7ecf\u5b58\u5728\u5219\u4e0d\u4f1a\u91cd\u590d\u521b\u5efa ,\u4f46\u662f\u4e0d\u4f1a\u62a5\u9519\nCREATE DATABASE IF NOT EXISTS mytest2 CHARACTER SET 'utf8';\nSHOW DATABASES;<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">2.2 \u7ba1\u7406\u6570\u636e\u5e93<\/h3>\n\n\n\n<p>\u67e5\u770b\u5f53\u524d\u6240\u6709\u7684\u6570\u636e\u5e93<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#1.2 \u7ba1\u7406\u6570\u636e\u5e93\n#\u67e5\u770b\u5f53\u524d\u8fde\u63a5\u4e2d\u7684\u6570\u636e\u5e93\u90fd\u6709\u54ea\u4e9b\nSHOW DATABASES;\n\n#\u5207\u6362\u6570\u636e\u5e93\nUSE atguigudb;\n\n#\u67e5\u770b\u5f53\u524d\u6570\u636e\u5e93\u4e2d\u4fdd\u5b58\u7684\u6570\u636e\u8868\nSHOW TABLES;\n\n#\u67e5\u770b\u5f53\u524d\u4f7f\u7528\u7684\u6570\u636e\u5e93\nSELECT DATABASE() FROM DUAL;\n\n#\u67e5\u770b\u6307\u5b9a\u6570\u636e\u5e93\u4e0b\u4fdd\u5b58\u7684\u6570\u636e\u8868\nSHOW TABLES FROM mysql;<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">2.3 \u4fee\u6539\u6570\u636e\u5e93<\/h3>\n\n\n\n<p><strong>DATABASE \u4e0d\u80fd\u6539\u540d\u3002<\/strong><\/p>\n\n\n\n<p>\u66f4\u6539\u6570\u636e\u5e93\u5b57\u7b26\u96c6<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>ALTER DATABASE \u6570\u636e\u5e93\u540d CHARACTER SET \u5b57\u7b26\u96c6;  #\u6bd4\u5982\uff1agbk\u3001utf8\u7b49\n\n\u4e3e\u4f8b:\nSHOW CREATE DATABASE mytest2;\n\nALTER DATABASE mytest2 CHARACTER SET 'utf8';<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">2.4 \u5220\u9664\u6570\u636e\u5e93<\/h3>\n\n\n\n<p>\u65b9\u5f0f1\uff1a\u5220\u9664\u6307\u5b9a\u7684\u6570\u636e\u5e93 DROP DATABASE \u6570\u636e\u5e93\u540d;<\/p>\n\n\n\n<p>\u65b9\u5f0f2\uff1a\u5220\u9664\u6307\u5b9a\u7684\u6570\u636e\u5e93\uff08 \u63a8\u8350\uff09 DROP DATABASE IF EXISTS \u6570\u636e\u5e93\u540d;<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#\u65b9\u5f0f1\uff1a\u5982\u679c\u8981\u5220\u9664\u7684\u6570\u636e\u5e93\u5b58\u5728\uff0c\u5219\u5220\u9664\u6210\u529f\u3002\u5982\u679c\u4e0d\u5b58\u5728\uff0c\u5219\u62a5\u9519\nDROP DATABASE mytest1;\n\nSHOW DATABASES;\n\n#\u65b9\u5f0f2\uff1a\u63a8\u8350\u3002\u5982\u679c\u8981\u5220\u9664\u7684\u6570\u636e\u5e93\u5b58\u5728\uff0c\u5219\u5220\u9664\u6210\u529f\u3002\u5982\u679c\u4e0d\u5b58\u5728\uff0c\u5219\u9ed8\u9ed8\u7ed3\u675f\uff0c\u4e0d\u4f1a\u62a5\u9519\u3002\nDROP DATABASE IF EXISTS mytest1;\n\nDROP DATABASE IF EXISTS mytest2;<\/code><\/pre>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>\u6574\u6570\u7c7b\u578b<\/td><td>TINYINT\u3001SMALLINT\u3001MEDIUMINT\u3001INT(\u6216INTEGER)\u3001BIGINT<\/td><\/tr><tr><td>\u6d6e\u70b9\u7c7b\u578b<\/td><td>FLOAT\u3001DOUBLE<\/td><\/tr><tr><td>\u5b9a\u70b9\u6570\u7c7b\u578b<\/td><td>DECIMAL<\/td><\/tr><tr><td>\u4f4d\u7c7b\u578b<\/td><td>BIT<\/td><\/tr><tr><td>\u65e5\u671f\u65f6\u95f4\u7c7b\u578b<\/td><td>YEAR\u3001TIME\u3001DATE\u3001DATETIME\u3001TIMESTAMP<\/td><\/tr><tr><td>\u6587\u672c\u5b57\u7b26\u4e32\u7c7b\u578b<\/td><td>CHAR\u3001VARCHAR\u3001TINYTEXT\u3001TEXT\u3001MEDIUMTEXT\u3001LONGTEXT<\/td><\/tr><tr><td>\u679a\u4e3e\u7c7b\u578b<\/td><td>ENUM<\/td><\/tr><tr><td>\u96c6\u5408\u7c7b\u578b<\/td><td>SET<\/td><\/tr><tr><td>\u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\u7c7b \u578b<\/td><td>BINARY\u3001VARBINARY\u3001TINYBLOB\u3001BLOB\u3001MEDIUMBLOB\u3001LONGBLOB<\/td><\/tr><tr><td>JSON\u7c7b\u578b<\/td><td>JSON\u5bf9\u8c61\u3001JSON\u6570\u7ec4<\/td><\/tr><tr><td>\u7a7a\u95f4\u6570\u636e\u7c7b\u578b<\/td><td>\u5355\u503c\uff1aGEOMETRY\u3001POINT\u3001LINESTRING\u3001POLYGON\uff1b \u96c6\u5408\uff1aMULTIPOINT\u3001MULTILINESTRING\u3001MULTIPOLYGON\u3001 GEOMETRYCOLLECTION<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">3. \u521b\u5efa\u8868&nbsp;<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>#2. \u5982\u4f55\u521b\u5efa\u6570\u636e\u8868\nUSE atguigudb;\n\nSHOW CREATE DATABASE atguigudb;  \u9ed8\u8ba4\u662futf8\n\nSHOW TABLES;\n\n#\u65b9\u5f0f1\uff1a\nCREATE TABLE IF NOT EXISTS myemp1 (  # \u9700\u8981\u7528\u6237\u5177\u5907\u521b\u5efa\u8868\u7684\u6743\u9650\u3002\n  id INT,\n  emp_name VARCHAR(15),   #\u4f7f\u7528VARCHAR\u6765\u5b9a\u4e49\u5b57\u7b26\u4e32\uff0c\u5fc5\u987b\u5728\u4f7f\u7528VARCHAR\u65f6\u6307\u660e\u5176\u957f\u5ea6\u3002\n  hire_date DATE\n);<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>#\u67e5\u770b\u8868\u7ed3\u6784\nDESC myemp1;\n#\u67e5\u770b\u521b\u5efa\u8868\u7684\u8bed\u53e5\u7ed3\u6784\nSHOW CREATE TABLE myemp1; #\u5982\u679c\u521b\u5efa\u8868\u65f6\u6ca1\u6709\u6307\u660e\u4f7f\u7528\u7684\u5b57\u7b26\u96c6\uff0c\u5219\u9ed8\u8ba4\u4f7f\u7528\u8868\u6240\u5728\u7684\u6570\u636e\u5e93\u7684\u5b57\u7b26\u96c6\u3002\n#\u67e5\u770b\u8868\u6570\u636e\nSELECT * FROM myemp1;\n\n#\u65b9\u5f0f2\uff1a\u57fa\u4e8e\u73b0\u6709\u7684\u8868\uff0c\u540c\u65f6\u5bfc\u5165\u6570\u636e\nCREATE TABLE myemp2\nAS\nSELECT employee_id,last_name,salary\nFROM employees;\n\nDESC myemp2;\nDESC employees;\n\nSELECT *\nFROM myemp2;\n<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>CREATE TABLE myemp3\nAS\nSELECT e.employee_id emp_id, e.last_name lname, d.department_name\nFROM employees e JOIN departments d\nON e.department_id = d.department_id;\n\n\n\u56fe\u4e2d\u7684SQL\u4ee3\u7801\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u8868myemp3\uff0c\u5176\u5185\u5bb9\u662f\u4e24\u4e2a\u73b0\u6709\u8868employees\u548cdepartments\u901a\u8fc7JOIN\u64cd\n\u4f5c\u5408\u5e76\u540e\u7684\u7ed3\u679c\u3002\u5177\u4f53\u6765\u8bf4\uff0c\u8fd9\u6761SQL\u8bed\u53e5\u6267\u884c\u4e86\u4ee5\u4e0b\u64cd\u4f5c\uff1a\n\u4f7f\u7528CREATE TABLE myemp3 AS\u8bed\u53e5\u521b\u5efa\u4e00\u4e2a\u65b0\u8868myemp3\u3002\n\u4f7f\u7528SELECT\u8bed\u53e5\u4eceemployees\u8868\u548cdepartments\u8868\u4e2d\u9009\u62e9\u6570\u636e\u3002\n\u4f7f\u7528JOIN\u64cd\u4f5c\u6839\u636edepartment_id\u5b57\u6bb5\u5c06employees\u8868\u548cdepartments\u8868\u8fde\u63a5\u8d77\u6765\uff0c\u8fd9\u610f\u5473\u7740\u53ea\u6709\u5f53\n\u4e24\u4e2a\u8868\u4e2d\u7684department_id\u76f8\u5339\u914d\u65f6\uff0c\u76f8\u5e94\u7684\u884c\u624d\u4f1a\u88ab\u9009\u4e2d\u3002\n\u9009\u62e9employees\u8868\u4e2d\u7684employee_id\u5b57\u6bb5\uff0c\u5e76\u5c06\u5176\u91cd\u547d\u540d\u4e3aemp_id\u3002\n\u9009\u62e9employees\u8868\u4e2d\u7684last_name\u5b57\u6bb5\uff0c\u5e76\u5c06\u5176\u91cd\u547d\u540d\u4e3alname\u3002\n\u9009\u62e9departments\u8868\u4e2d\u7684department_name\u5b57\u6bb5\u3002\n\u6700\u7ec8\uff0c\u8fd9\u6761\u8bed\u53e5\u521b\u5efa\u4e86\u4e00\u4e2a\u5305\u542b\u5458\u5de5ID\u3001\u5458\u5de5\u59d3\u6c0f\u548c\u90e8\u95e8\u540d\u79f0\u7684\u65b0\u8868myemp3\uff0c\u5176\u4e2d\u6bcf\u4e2a\u5458\u5de5\u90fd\u4e0e\u5176\u6240\u5c5e\u7684\n\u90e8\u95e8\u5173\u8054\u8d77\u6765\u3002\u8fd9\u4e2a\u65b0\u8868\u53ef\u4ee5\u7528\u4e8e\u8fdb\u4e00\u6b65\u7684\u67e5\u8be2\u548c\u5206\u6790\uff0c\u4f8b\u5982\u67e5\u627e\u7279\u5b9a\u90e8\u95e8\u7684\u6240\u6709\u5458\u5de5\u6216\u7279\u5b9a\u5458\u5de5\u7684\u90e8\u95e8\n\u4fe1\u606f\u3002<\/code><\/pre>\n\n\n\n<p>SELECT *<br>FROM myemp3;<\/p>\n\n\n\n<p>\u901a\u8fc7\u4e0a\u9762\u4e24\u53e5\u67e5\u8be2\u4e00\u4e0b\uff0c\u53d1\u73b0\u5c31\u662f\u539f\u6570\u636e\u5e93\u4e2d\u7684\u5185\u5bb9\u56e0\u6b64\u6709<\/p>\n\n\n\n<p><strong>#\u8bf4\u660e1\uff1a\u67e5\u8be2\u8bed\u53e5\u4e2d\u5b57\u6bb5\u7684\u522b\u540d\uff0c\u53ef\u4ee5\u4f5c\u4e3a\u65b0\u521b\u5efa\u7684\u8868\u7684\u5b57\u6bb5\u7684\u540d\u79f0\u3002<br>#\u8bf4\u660e2\uff1a\u6b64\u65f6\u7684\u67e5\u8be2\u8bed\u53e5\u53ef\u4ee5\u7ed3\u6784\u6bd4\u8f83\u4e30\u5bcc\uff0c\u4f7f\u7528\u524d\u9762\u7ae0\u8282\u8bb2\u8fc7\u7684\u5404\u79cdSELECT<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#\u7ec3\u4e601\uff1a\u521b\u5efa\u4e00\u4e2a\u8868employees_copy\uff0c\u5b9e\u73b0\u5bf9employees\u8868\u7684\u590d\u5236\uff0c\u5305\u62ec\u8868\u6570\u636e\nCREATE TABLE employees_copy\nAS\nSELECT *\nFROM employees;\n\nSELECT * FROM employees_copy;\n\n#\u7ec3\u4e602\uff1a\u521b\u5efa\u4e00\u4e2a\u8868employees_blank\uff0c\u5b9e\u73b0\u5bf9employees\u8868\u7684\u590d\u5236\uff0c\u4e0d\u5305\u62ec\u8868\u6570\u636e\nCREATE TABLE employees_blank\nAS\nSELECT *\nFROM employees\n#where department_id &gt; 10000;\nWHERE 1 = 2; #\u5c71\u65e0\u9675\uff0c\u5929\u5730\u5408\uff0c\u4e43\u6562\u4e0e\u541b\u7edd\u3002\n#\u8fd9\u91cc\u5c31\u662f\u627e\u4e00\u4e2a\u4e0d\u53ef\u80fd\u7684\u6761\u4ef6\uff0c\u4ece\u800c\u9694\u7edd\u6240\u6709\u7684\u5185\u5bb9\u53ea\u7559\n\n\nSELECT * FROM employees_blank;<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">4. \u4fee\u6539\u8868--------------alter&nbsp; table<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>DESC myemp1;\n\n# 3.1 \u6dfb\u52a0\u4e00\u4e2a\u5b57\u6bb5\nALTER TABLE myemp1\nADD salary DOUBLE(10,2);  #\u9ed8\u8ba4\u6dfb\u52a0\u5230\u8868\u4e2d\u7684\u6700\u540e\u4e00\u4e2a\u5b57\u6bb5\u7684\u4f4d\u7f6e\n\nALTER TABLE myemp1\nADD phone_number VARCHAR(20) FIRST; #\u7b2c\u4e00\u4f4d\n\nALTER TABLE myemp1\nADD email VARCHAR(45) AFTER emp_name;<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code># 3.2 \u4fee\u6539\u4e00\u4e2a\u5b57\u6bb5\uff1a\u6570\u636e\u7c7b\u578b\u3001\u957f\u5ea6\u3001\u9ed8\u8ba4\u503c\uff08\u7565\uff09\nALTER TABLE myemp1\nMODIFY emp_name VARCHAR(25) ;\n\nALTER TABLE myemp1\nMODIFY emp_name VARCHAR(35) DEFAULT 'aaa';<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code># 3.3 \u91cd\u547d\u540d\u4e00\u4e2a\u5b57\u6bb5\nALTER TABLE myemp1\nCHANGE salary monthly_salary DOUBLE(10,2);\n\nALTER TABLE myemp1\nCHANGE email my_email VARCHAR(50);<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code># 3.4 \u5220\u9664\u4e00\u4e2a\u5b57\u6bb5\nALTER TABLE myemp1\nDROP COLUMN my_email;<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>#4. \u91cd\u547d\u540d\u8868\n#\u65b9\u5f0f1\uff1a\nRENAME TABLE myemp1\nTO myemp11;\n\nDESC myemp11;\n\n#\u65b9\u5f0f2\uff1a\nALTER TABLE myemp2\nRENAME TO myemp12;\n\nDESC myemp12;<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>#5. \u5220\u9664\u8868                \u65e0\u6cd5\u56de\u6eda\n#\u4e0d\u5149\u5c06\u8868\u7ed3\u6784\u5220\u9664\u6389\uff0c\u540c\u65f6\u8868\u4e2d\u7684\u6570\u636e\u4e5f\u5220\u9664\u6389\uff0c\u91ca\u653e\u8868\u7a7a\u95f4\nDROP TABLE IF EXISTS myemp2;\n\nDROP TABLE IF EXISTS myemp12;<\/code><\/pre>\n\n\n\n<p>IF EXISTS \u7684\u542b\u4e49\u4e3a\uff1a\u5982\u679c\u5f53\u524d\u6570\u636e\u5e93\u4e2d\u5b58\u5728\u76f8\u5e94\u7684\u6570\u636e\u8868\uff0c\u5219\u5220\u9664\u6570\u636e\u8868\uff1b\u5982\u679c\u5f53\u524d\u6570\u636e\u5e93\u4e2d\u4e0d\u5b58\u5728\u76f8\u5e94\u7684\u6570\u636e\u8868\uff0c\u5219\u5ffd\u7565\u5220\u9664\u8bed\u53e5\uff0c\u4e0d\u518d\u6267\u884c\u5220\u9664\u6570\u636e\u8868\u7684\u64cd\u4f5c\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#6. \u6e05\u7a7a\u8868\n\n#\u6e05\u7a7a\u8868\uff0c\u8868\u793a\u6e05\u7a7a\u8868\u4e2d\u7684\u6240\u6709\u6570\u636e\uff0c\u4f46\u662f\u8868\u7ed3\u6784\u4fdd\u7559\u3002\u6267\u884c\u4e86commit\u5c31\u662f\u6c38\u4e45\u7684\u4fdd\u5b58\u4e86\u6570\u636e\uff0c\n\u6570\u636e\u5c31\u5df2\u7ecf\u4fdd\u5b58\u5230\u4e86\u6570\u636e\u5e93\u4e2d\uff0c\u4e0d\u80fd\u56de\u6eda\n\nSELECT * FROM employees_copy;\n\nTRUNCATE TABLE employees_copy;\n\nSELECT * FROM employees_copy;\n\nDESC employees_copy;<\/code><\/pre>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\u3010\u53c2\u8003\u3011TRUNCATE TABLE \u6bd4 DELETE \u901f\u5ea6\u5feb\uff0c\u4e14\u4f7f\u7528\u7684\u7cfb\u7edf\u548c\u4e8b\u52a1\u65e5\u5fd7\u8d44\u6e90\u5c11\uff0c\u4f46 TRUNCATE \u65e0 \u4e8b\u52a1\u4e14\u4e0d\u89e6\u53d1 TRIGGER\uff0c\u6709\u53ef\u80fd\u9020\u6210\u4e8b\u6545\uff0c\u6545\u4e0d\u5efa\u8bae\u5728\u5f00\u53d1\u4ee3\u7801\u4e2d\u4f7f\u7528\u6b64\u8bed\u53e5\u3002<\/p>\n\n\n\n<p>\u8bf4\u660e\uff1aTRUNCATE TABLE \u5728\u529f\u80fd\u4e0a\u4e0e\u4e0d\u5e26 WHERE \u5b50\u53e5\u7684 DELETE \u8bed\u53e5\u76f8\u540c\u3002<\/p>\n<\/blockquote>\n\n\n\n<p><strong>7 . DCL \u4e2d COMMIT \u548c ROLLBACK<br># COMMIT:\u63d0\u4ea4\u6570\u636e\u3002\u4e00\u65e6\u6267\u884cCOMMIT\uff0c\u5219\u6570\u636e\u5c31\u88ab\u6c38\u4e45\u7684\u4fdd\u5b58\u5728\u4e86\u6570\u636e\u5e93\u4e2d\uff0c\u610f\u5473\u7740\u6570\u636e\u4e0d\u53ef\u4ee5\u56de\u6eda<br># ROLLBACK:\u56de\u6eda\u6570\u636e\u3002\u4e00\u65e6\u6267\u884cROLLBACK,\u5219\u53ef\u4ee5\u5b9e\u73b0\u6570\u636e\u7684\u56de\u6eda\u3002\u56de\u6eda\u5230\u6700\u8fd1\u7684\u4e00\u6b21COMMIT\u4e4b\u540e&nbsp;<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#8. \u5bf9\u6bd4 TRUNCATE TABLE \u548c DELETE FROM \n# \u76f8\u540c\u70b9\uff1a\u90fd\u53ef\u4ee5\u5b9e\u73b0\u5bf9\u8868\u4e2d\u6240\u6709\u6570\u636e\u7684\u5220\u9664\uff0c\u540c\u65f6\u4fdd\u7559\u8868\u7ed3\u6784\u3002\n# \u4e0d\u540c\u70b9\uff1a\n#TRUNCATE TABLE\uff1a\u4e00\u65e6\u6267\u884c\u6b64\u64cd\u4f5c\uff0c\u8868\u6570\u636e\u5168\u90e8\u6e05\u9664\u3002\u540c\u65f6\uff0c\u6570\u636e\u662f\u4e0d\u53ef\u4ee5\u56de\u6eda\u7684\n#DELETE FROM\uff1a\u4e00\u65e6\u6267\u884c\u6b64\u64cd\u4f5c\uff0c\u8868\u6570\u636e\u53ef\u4ee5\u5168\u90e8\u6e05\u9664\uff08\u4e0d\u5e26WHERE\uff09\u3002\u540c\u65f6\uff0c\u6570\u636e\u662f\u53ef\u4ee5\u5b9e\u73b0\u56de\u6eda\u7684<\/code><\/pre>\n\n\n\n<p>9. DDL \u548c DML \u7684\u8bf4\u660e<\/p>\n\n\n\n<p>&nbsp; \u2460 DDL\u7684\u64cd\u4f5c\u4e00\u65e6\u6267\u884c\uff0c\u5c31\u4e0d\u53ef\u56de\u6eda\u3002\u6307\u4ee4SET autocommit = FALSE\u5bf9DDL\u64cd\u4f5c\u5931\u6548\u3002(\u56e0\u4e3a\u5728\u6267\u884c\u5b8cDDL&nbsp;\u64cd\u4f5c\u4e4b\u540e\uff0c\u4e00\u5b9a\u4f1a\u6267\u884c\u4e00\u6b21COMMIT\u3002\u800c\u6b64COMMIT\u64cd\u4f5c\u4e0d\u53d7SET autocommit = FALSE\u5f71\u54cd\u7684\u3002)<\/p>\n\n\n\n<p>&nbsp; \u2461 DML\u7684\u64cd\u4f5c\u9ed8\u8ba4\u60c5\u51b5\uff0c\u4e00\u65e6\u6267\u884c\uff0c\u4e5f\u662f\u4e0d\u53ef\u56de\u6eda\u7684\u3002\u4f46\u662f\uff0c\u5982\u679c\u5728\u6267\u884cDML\u4e4b\u524d\uff0c\u6267\u884c\u4e86<br>SET autocommit = FALSE\uff0c\u5219\u6267\u884c\u7684DML\u64cd\u4f5c\u5c31\u53ef\u4ee5\u5b9e\u73b0\u56de\u6eda\u3002<\/p>\n\n\n\n<p>\u63a5\u4e0b\u6765\u8fdb\u5165\u6f14\u793a\u73af\u8282\uff0c\u63a7\u5236\u53d8\u91cf\u6cd5\uff0c\u9009\u62e9\u4e0d\u540c\u9009\u9879\u6765<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code># \u6f14\u793a\uff1aDELETE FROM \n#1)\nCOMMIT;\n\n#2)\nSELECT *\nFROM myemp3;\n\n#3)\nSET autocommit = FALSE;\n\n#4)\nDELETE FROM myemp3;\n\n#5)\nSELECT *\nFROM myemp3;\n\n#6)\nROLLBACK;\n\n#7)\nSELECT *\nFROM myemp3;\n<\/code><\/pre>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\u963f\u91cc\u5f00\u53d1\u89c4\u8303\uff1a<\/p>\n\n\n\n<p>\u3010\u53c2\u8003\u3011TRUNCATE TABLE \u6bd4 DELETE \u901f\u5ea6\u5feb\uff0c\u4e14\u4f7f\u7528\u7684\u7cfb\u7edf\u548c\u4e8b\u52a1\u65e5\u5fd7\u8d44\u6e90\u5c11\uff0c\u4f46 TRUNCATE \u65e0\u4e8b\u52a1\u4e14\u4e0d\u89e6\u53d1 TRIGGER\uff0c\u6709\u53ef\u80fd\u9020\u6210\u4e8b\u6545\uff0c\u6545\u4e0d\u5efa\u8bae\u5728\u5f00\u53d1\u4ee3\u7801\u4e2d\u4f7f\u7528\u6b64\u8bed\u53e5\u3002<\/p>\n\n\n\n<p>\u8bf4\u660e\uff1aTRUNCATE TABLE \u5728\u529f\u80fd\u4e0a\u4e0e\u4e0d\u5e26 WHERE \u5b50\u53e5\u7684 DELETE \u8bed\u53e5\u76f8\u540c\u3002<\/p>\n<\/blockquote>\n\n\n\n<p><a href=\"https:\/\/www.bilibili.com\/video\/BV1iq4y1u7vj?t=450.8&amp;p=53\" target=\"_blank\"  rel=\"nofollow\" >53-\u963f\u91ccMySQL\u547d\u540d\u89c4\u8303\u53caMySQL8DDL\u7684\u539f\u5b50\u5316_\u54d4\u54e9\u54d4\u54e9_bilibili<\/a>\u00a0<img decoding=\"async\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/563b4a5442b44d0db4e5fc88f90690fa.png\" alt=\"\"><img decoding=\"async\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/f6382935365f4353bb60cfbc5870198c.png\" alt=\"\"><img decoding=\"async\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/13f590dfac694e98970c86bbf2855ebb.png\" alt=\"\"><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">&nbsp;\u8bfe\u540e\u7ec3\u4e60<\/h2>\n\n\n\n<h4 class=\"wp-block-heading\">\u7b2c\u4e00\u90e8\u5206<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>#1. \u521b\u5efa\u6570\u636e\u5e93test01_office, \u6307\u660e\u5b57\u7b26\u96c6\u4e3autf8\u3002\u5e76\u5728\u6b64\u6570\u636e\u5e93\u4e0b\u6267\u884c\u4e0b\u8ff0\u64cd\u4f5c\n\n#2. \u521b\u5efa\u8868dept01\n\/*\n\u5b57\u6bb5    \u7c7b\u578b\nid      INT(7)\nNAME    VARCHAR(25)\n*\/\n\n#3. \u5c06\u8868departments\u4e2d\u7684\u6570\u636e\u63d2\u5165\u65b0\u8868dept02\u4e2d\n\n#4. \u521b\u5efa\u8868emp01\n\/*\n\u5b57\u6bb5    \u7c7b\u578b\nid      INT(7)\nfirst_name VARCHAR (25)\nlast_name VARCHAR(25)\ndept_id  INT(7)\n*\/\n\n#5. \u5c06\u5217last_name\u7684\u957f\u5ea6\u589e\u52a0\u523050\n\n#6. \u6839\u636e\u8868employees\u521b\u5efaemp02\n\n#7. \u5220\u9664\u8868emp01\n\n#8. \u5c06\u8868emp02\u91cd\u547d\u540d\u4e3aemp01\n\n#9. \u5728\u8868dept02\u548cemp01\u4e2d\u6dfb\u52a0\u65b0\u5217test_column\uff0c\u5e76\u68c0\u67e5\u6240\u4f5c\u7684\u64cd\u4f5c\n\n#10. \u76f4\u63a5\u5220\u9664\u8868emp01\u4e2d\u7684\u5217 department_id<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>#1. \u521b\u5efa\u6570\u636e\u5e93test01_office,\u6307\u660e\u5b57\u7b26\u96c6\u4e3autf8\u3002\u5e76\u5728\u6b64\u6570\u636e\u5e93\u4e0b\u6267\u884c\u4e0b\u8ff0\u64cd\u4f5c\nCREATE DATABASE IF NOT EXISTS test01_office CHARACTER SET 'utf8';\nUSE test01_office;<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>#2. \u521b\u5efa\u8868dept01\n\/*\n\u5b57\u6bb5    \u7c7b\u578b\nid      INT(7)\nNAME    VARCHAR(25)\n*\/\n\n CREATE TABLE dept01(\n id INT(7),\n NAME VARCHAR(25)\n );<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>#3. \u5c06\u8868departments\u4e2d\u7684\u6570\u636e\u63d2\u5165\u65b0\u8868dept02\u4e2d\nCREATE TABLE dept02\nAS\nSELECT *\nFROM atguigudb.departments;<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code>#4. \u521b\u5efa\u8868emp01\n\/*\n\u5b57\u6bb5    \u7c7b\u578b\nid      INT(7)\nfirst_name VARCHAR (25)\nlast_name VARCHAR(25)\ndept_id  INT(7)\n*\/\n\n\nCREATE TABLE emp01(\nid INT(7),\nfirst_name VARCHAR(25),\nlast_name VARCHAR(25),\ndept_id INT(7)\n);<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code> #5. \u5c06\u5217last_name\u7684\u957f\u5ea6\u589e\u52a0\u523050\n DESC emp01;\n ALTER TABLE emp01\n MODIFY last_name VARCHAR(50);<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code> #6. \u6839\u636e\u8868employees\u521b\u5efaemp02\n CREATE TABLE emp02\n AS\n SELECT *\n FROM atguigudb.`employees`;\n SHOW TABLES FROM test01_office;<\/code><\/pre>\n\n\n\n<pre class=\"wp-block-code\"><code> #7. \u5220\u9664\u8868emp01\n DROP TABLE IF EXISTS emp01;\n #8. \u5c06\u8868emp02\u91cd\u547d\u540d\u4e3aemp01\n #ALTER TABLE emp02 RENAME TO emp01;\n RENAME TABLE emp02 TO emp01;\n #9. \u5728\u8868dept02\u548cemp01\u4e2d\u6dfb\u52a0\u65b0\u5217test_column\uff0c\u5e76\u68c0\u67e5\u6240\u4f5c\u7684\u64cd\u4f5c\n ALTER TABLE emp01 ADD test_column VARCHAR(10);\n DESC emp01;\n ALTER TABLE dept02 ADD test_column VARCHAR(10);\n DESC dept02;\n #10.\u76f4\u63a5\u5220\u9664\u8868emp01\u4e2d\u7684\u5217 department_id\n ALTER TABLE emp01\n DROP COLUMN department_id;<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\">\u7b2c\u4e8c\u90e8\u5206<\/h4>\n\n\n\n<p><img loading=\"lazy\" decoding=\"async\" height=\"765\" width=\"894\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/d90248f238b64b1fa84ecfbd33f64ab5.png\" alt=\"\"><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#1\u3001\u521b\u5efa\u6570\u636e\u5e93 test02_market\n CREATE DATABASE IF NOT EXISTS test02_market CHARACTER SET 'utf8';\n #\u6307\u5b9a\u5bf9\u54ea\u4e2a\u6570\u636e\u5e93\u8fdb\u884c\u64cd\u4f5c\nUSE test02_market;\n #2\u3001\u521b\u5efa\u6570\u636e\u8868 customers\n CREATE TABLE customers(\n c_num INT ,\n c_name VARCHAR(50),\n c_contact VARCHAR(50),\nc_city VARCHAR(50),\n c_birth DATE\n );\n #3\u3001\u5c06c_contact\u5b57\u6bb5\u63d2\u5165\u5230c_birth\u5b57\u6bb5\u540e\u9762\nALTER TABLE customers MODIFY c_contact VARCHAR(50) AFTER c_birth;\n #4\u3001\u5c06c_name\u5b57\u6bb5\u6570\u636e\u7c7b\u578b\u6539\u4e3a varchar(70)\n ALTER TABLE customers MODIFY c_name VARCHAR(70);\n #5\u3001\u5c06c_contact\u5b57\u6bb5\u6539\u540d\u4e3ac_phone\n ALTER TABLE customers CHANGE c_contact c_phone VARCHAR(50);\n #6\u3001\u589e\u52a0c_gender\u5b57\u6bb5\u5230c_name\u540e\u9762\uff0c\u6570\u636e\u7c7b\u578b\u4e3achar(1)\n ALTER TABLE customers ADD c_gender CHAR(1) AFTER c_name;\n #7\u3001\u5c06\u8868\u540d\u6539\u4e3acustomers_info\n RENAME TABLE customers TO customers_info;\n #ALTER TABLE customers RENAME TO customers_info;\n #8\u3001\u5220\u9664\u5b57\u6bb5c_city\n ALTER TABLE customers_info DROP COLUMN c_city ;<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\">\u7b2c\u4e09\u90e8\u5206<\/h4>\n\n\n\n<p><img loading=\"lazy\" decoding=\"async\" height=\"499\" width=\"922\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/b708d5f12e4f4363a286626fe2f247f9.png\" alt=\"\"><img loading=\"lazy\" decoding=\"async\" height=\"840\" width=\"905\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/fbefeaf3b14d48d8ad1168afd5736a17.png\" alt=\"\"><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#1. \u521b\u5efa\u6570\u636e\u5e93test03_company\nCREATE DATABASE IF NOT EXISTS test03_company CHARACTER SET 'utf8';\n\n#\u6307\u5b9a\u4f7f\u7528\u54ea\u4e2a\u6570\u636e\u5e93\uff0c\u5373\u4e0b\u9762\u7684sql\u8bed\u53e5\u662f\u9488\u5bf9\u54ea\u4e2a\u6570\u636e\u5e93\u7684\nUSE test03_company;\n\n# 2. \u521b\u5efa\u8868offices\nCREATE TABLE offices (\n    officeCode INT,\n    city VARCHAR(30),\n    address VARCHAR(50),\n    country VARCHAR(50),\n    postalCode VARCHAR(25)\n);\n\n# 3. \u521b\u5efa\u8868employees\nCREATE TABLE IF NOT EXISTS employees (\n    empNum INT,\n    lastName VARCHAR(50),\n    firstName VARCHAR(50),\n    mobile VARCHAR(25),\n    `code` INT ,\n    jobTitle VARCHAR(50),\n    birth DATE,\n    note VARCHAR(255),\n    sex VARCHAR(5)\n);\n\n# 4. \u5c06\u8868employees\u7684mobile\u5b57\u6bb5\u4fee\u6539\u5230code\u5b57\u6bb5\u540e\u9762\nALTER TABLE employees\nMODIFY mobile VARCHAR(20) AFTER `code`;\n\n# 5. \u5c06\u8868employees\u7684birth\u5b57\u6bb5\u6539\u540d\u4e3abirthday\nALTER TABLE employees CHANGE birth birthday DATE;\n\n# 6. \u4fee\u6539sex\u5b57\u6bb5\uff0c\u6570\u636e\u7c7b\u578b\u4e3achar(1)\nALTER TABLE employees MODIFY sex CHAR(1);\n\n# 7. \u5220\u9664\u5b57\u6bb5note\nALTER TABLE employees DROP COLUMN note;\n\n# 8. \u589e\u52a0\u5b57\u6bb5\u540dfavorite_activity, \u6570\u636e\u7c7b\u578b\u4e3avarchar(100)\nALTER TABLE employees ADD COLUMN favorite_activity VARCHAR(100);\n\n# 9. \u5c06\u8868employees\u7684\u540d\u79f0\u4fee\u6539\u4e3a employees_info\nRENAME TABLE employees TO employees_info;\n\nDESC employees_info;<img loading=\"lazy\" decoding=\"async\" height=\"15\" width=\"15\" src=\"blob:https:\/\/eve2333.top\/ee834387-4824-46a1-9528-d2b2c2e450f4\"><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp;&nbsp;\u7b2c10\u7ae0_\u521b\u5efa\u548c\u7ba1\u7406\u8868 DDL\uff1a\u6570\u636e\u5b9a\u4e49\u8bed\u8a00\u3002CREATE&nbsp; &nbsp;\\ALTER\\&#038;nbs &#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"emotion":"","emotion_color":"","title_style":"","license":"","footnotes":""},"categories":[2],"tags":[16],"class_list":["post-854","post","type-post","status-publish","format-standard","hentry","category-2","tag-sql"],"_links":{"self":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/854","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=854"}],"version-history":[{"count":1,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/854\/revisions"}],"predecessor-version":[{"id":855,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/854\/revisions\/855"}],"wp:attachment":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=854"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=854"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=854"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}