Basic database operations in MySQL

1、 view the database

show databases;

This command can view the current database service , There are several databases , as follows ：

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sakila             |
| sys                |
| world              |
+--------------------+
6 rows in set (0.00 sec)

mysql>

2、 Create database

create database db_name;

This command can create a database , as follows ：

mysql> create database yunweijia;
Query OK, 1 row affected (0.01 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sakila             |
| sys                |
| world              |
| yunweijia          |
+--------------------+
7 rows in set (0.00 sec)

mysql>

Someone asked , How to check the status and process of database creation , Use the following command ;

show create database db_name

Example ：

mysql> show create database yunweijia;
+-----------+-------------------------------------------------------------------------------------------------------------------------------------+
| Database  | Create Database                                                                                                                     |
+-----------+-------------------------------------------------------------------------------------------------------------------------------------+
| yunweijia | CREATE DATABASE `yunweijia` /*!40100 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci */ /*!80016 DEFAULT ENCRYPTION='N' */ |
+-----------+-------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

In this way, we can see when we create the database , What parameters does he add to you by default .

3、 Delete database

If the database is deleted , The data in it has also been deleted , Be sure to operate with caution . Don't even do this .

drop database db_name;

as follows ：

mysql> drop database yunweijia;
Query OK, 0 rows affected (0.01 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sakila             |
| sys                |
| world              |
+--------------------+
6 rows in set (0.00 sec)

mysql>

4、mysql8.0 New characteristics , All is InnoDB type

from MySQL 8.0 Start , The system tables are all transactional InnoDB surface , default MySQL The instance will not contain any MyISAM surface , Unless you create it manually MyISAM surface .

select distinct(ENGINE) from information_schema.tables;

Let's see one first 5.7 Version database ;

And then look at 8.0 Version information ;

mysql> select distinct(ENGINE) from information_schema.tables;
+--------------------+
| ENGINE             |
+--------------------+
| InnoDB             |
| NULL               |
| PERFORMANCE_SCHEMA |
| CSV                |
+--------------------+
4 rows in set (0.01 sec)

mysql>

thus , In this paper, the end .

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