What are the basic commands for operating MySQL
This article is mainly about what are the basic commands for operating MySQL. If you are interested, let's take a look at this article. I believe it is of some reference value to you after reading the basic commands for operating MySQL.
Operating system: CentOS
Database system: MySQL
[root@sky9896~] # mysql-h localhost-P 3306-uroot-p # Note the P before the port number is the size
Mysql > select version (), current_date; # retrieves the current database version and current time
+-+ +
| | version () | current_date | |
+-+ +
| | 5.5.52-cll-lve | 2017-08-09 |
+-+ +
1row in set (0.00 sec)
Mysql > use employees # Open the database
Databasechanged
Mysql > select database (); # query the current database
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| | database () |
+-+
| | employees |
+-+
1row in set (0.00 sec)
Mysql > show tables; # shows all the tables in the database
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| | Tables_in_employees |
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| | departments |
| | dept_emp |
| | dept_manager |
| | employees |
| | salaries |
| | titles |
+-+
6rows in set (0.00 sec)
Mysql > create table employees_2 (# create tables
-> emp_no int (11) NOT NULL
-> birth_date date NOT null
-> first_name varchar (14) not null
-> last_name varchar (16) not null
-> gender enum ('Maureen F') not null
-> hire_date date not null
-> primary key (emp_no)
->) engine=innodb default charset=latin1
QueryOK, 0 rows affected (0.19 sec)
Mysql > desc employees_2; # shows the table structure
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| | Field | Type | Null | Key | Default | Extra | |
+-+ +
| | emp_no | int (11) | NO | PRI | NULL |
| | birth_date | date | NO | | NULL |
| | first_name | varchar (14) | NO | | NULL |
| | last_name | varchar (16) | NO | | NULL |
| | gender | enum ('Mitchell dagger F') | NO | | NULL | |
| | hire_date | date | NO | | NULL |
+-+ +
6rows in set (0.02 sec)
Mysql > create table T1 (an integer,b char (10))
QueryOK, 0 rows affected (0.11 sec)
Mysql > show tables
+-+
| | Tables_in_employees |
+-+
| | departments |
| | dept_emp |
| | dept_manager |
| | employees |
| | employees_2 |
| | salaries |
| | T1 |
| | titles |
+-+
8rows in set (0.00 sec)
Mysql > alter table T1 rename T2; # modify the table name
QueryOK, 0 rows affected (0.05 sec)
Mysql > show tables
+-+
| | Tables_in_employees |
+-+
| | departments |
| | dept_emp |
| | dept_manager |
| | employees |
| | employees_2 |
| | salaries |
| | T2 |
| | titles |
+-+
8rows in set (0.00 sec)
Mysql > desc T2
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| | Field | Type | Null | Key | Default | Extra | |
+-+ +
| | a | int (11) | YES | | NULL |
| | b | char (10) | YES | | NULL |
+-+ +
2rows in set (0.00 sec)
Mysql > alter table T2 modify a tinyint notnull,change b c char (20); # modify list
QueryOK, 0 rows affected (0.25 sec)
Records:0 Duplicates: 0 Warnings: 0
Mysql > desc T2
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| | Field | Type | Null | Key | Default | Extra | |
+-+ +
| | a | tinyint (4) | NO | | NULL |
| | c | char (20) | YES | | NULL |
+-+ +
2rows in set (0.00 sec)
Ysql > alter table T2 add d timestamp
QueryOK, 0 rows affected (0.19 sec)
Records:0 Duplicates: 0 Warnings: 0
Mysql > desc T2
+-- +
| | Field | Type | Null | Key | Default | Extra | |
+-- +
| | a | tinyint (4) | NO | | NULL |
| | c | char (20) | YES | | NULL |
| | d | timestamp | NO | | CURRENT_TIMESTAMP | on updateCURRENT_TIMESTAMP | |
+-- +
3rows in set (0.00 sec)
Mysql > alter table T2 add index (d), add index (a); # add index
Mysql > show keys from T2
Mysql > insert into employees (emp_no,birth_date,first_name,last_name,gender,hire_date) values ('1111112 / 8 / 9 / 2017 / 8 / 9 / 2017 / 08 / 09 / 2017)
QueryOK, 1 row affected (0.09 sec)
Mysql > select * from employees where emp_no=1111112
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| | emp_no | birth_date | first_name | last_name | gender | hire_date | |
+-+ +
| | 1111112 | 2017-08-09 | wu | haiming | M | 2017-08-09 |
+-+ +
1row in set (0.00 sec)
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