Mysql怎样创建数据库
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小编给大家分享一下Mysql如何创建数据库，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！ 4.1 create and drop database C:\Users\admin>mysql -h localhost -u root -pmysql mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 3 Server version: 5.7.14 MySQL Community Server (GPL) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | | test | +--------------------+ 5 rows in set (0.00 sec) mysql> create database example; #create database Query OK, 1 row affected (0.04 sec) mysql> show databases; #显示databases +--------------------+ | Database | +--------------------+ | information_schema | | example | | mysql | | performance_schema | | sys | | test | +--------------------+ 6 rows in set (0.00 sec) mysql> drop database example; #drop database; Query OK, 0 rows affected (0.04 sec) mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | | test | +--------------------+ 5 rows in set (0.00 sec) mysql> create database mysql; ERROR 1007 (HY000): Can't create database 'mysql'; database exists mysql> create database mydata; Query OK, 1 row affected (0.01 sec) 4.2 存储引擎 mysql> show engines \G *************************** 1. row *************************** Engine: InnoDB Support: DEFAULT Comment: Supports transactions, row-level locking, and foreign keys Transactions: YES XA: YES Savepoints: YES *************************** 2. row *************************** Engine: MRG_MYISAM Support: YES Comment: Collection of identical MyISAM tables Transactions: NO XA: NO Savepoints: NO *************************** 3. row *************************** Engine: MEMORY Support: YES Comment: Hash based, stored in memory, useful for temporary tables Transactions: NO XA: NO Savepoints: NO *************************** 4. row *************************** Engine: BLACKHOLE Support: YES Comment: /dev/null storage engine (anything you write to it disappears) Transactions: NO XA: NO Savepoints: NO *************************** 5. row *************************** Engine: MyISAM Support: YES Comment: MyISAM storage engine Transactions: NO XA: NO Savepoints: NO *************************** 6. row *************************** Engine: CSV Support: YES Comment: CSV storage engine Transactions: NO XA: NO Savepoints: NO *************************** 7. row *************************** Engine: ARCHIVE Support: YES Comment: Archive storage engine Transactions: NO XA: NO Savepoints: NO *************************** 8. row *************************** Engine: PERFORMANCE_SCHEMA Support: YES Comment: Performance Schema Transactions: NO XA: NO Savepoints: NO *************************** 9. row *************************** Engine: FEDERATED Support: NO Comment: Federated MySQL storage engine Transactions: NULL XA: NULL Savepoints: NULL 9 rows in set (0.00 sec) mysql> 4.2.1 InnoDB engine InnoDB是mysql数据库中的存储引擎,innodb给mysql的表提供了事务，回滚，崩溃修复能力，多版本并发控制的事务安全 (1) Innodb那个。存储引擎支持自动增长列auto_increment. (2) Innodb存储引擎支持外键(foreign key) (3) Innodb存储引擎，创建的表的表结构在.frm文件中，数据和索引存储在innodb_data_home_dir和innodb_data_file_path定义的表空间 (4) Innodb存储引擎的缺点是读写效率稍差，占用的数据空间相对较大。 4.2.2 MyISAM engine MyISAM是mysql中常见的存储引擎 MyISAM存储引擎的表存储成三个文件。文件的名字与表名相同，扩展名包括frm,MYD,MYI, .其中frm为扩展名的文件存储表的结构；MYD(MYData)为扩展名的文件存储数据，MYI(MYindex)为扩展名的文件存储引擎 MyISAM存储引擎的优势在于占用空间小，处理速度快。缺点是不支持事务的完整性和并发性。 4.2.3 MEMORY 特殊存储引擎,表结构在disk上，数据在内存中。 （编辑：银川站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
