MYSQL Beginner's Guide to Using the Command Line

MYSQL Beginner’s Guide and Introduction

1. Connect to MYSQL.
Format: mysql -h host address -u username -p user password
1. Example 1: Connect to MYSQL on this machine.
First open the DOS window, then enter the directory mysqlbin, and then type the command mysql -uroot -p. After pressing Enter, you will be prompted to enter your password. If MYSQL has just been installed, the super user root does not have a password, so you can enter directly by pressing Enter. In MYSQL, the prompt of MYSQL is: mysql>
2. Example 2: Connect to MYSQL on the remote host. Assume that the IP of the remote host is: 110
.110.110.110, the user name is root, and the password is abcd123. Then type the following command:
mysql -h110.110.110.110 -uroot -pabcd123
(Note: u and root do not need to add spaces, the same goes for others)
3. Exit the MYSQL command: exit (Enter)

2. change Password.
Format: mysqladmin -u username -p old password password new password
1. Example 1: Add a password ab12 to root. First, enter the directory mysqlbin under DOS, and then type the following command (do not add the command character in password)
mysqladmin -uroot password ab12
Note: Because root does not have a password at the beginning, the -p old password item can be omitted.
2. Example 2: Change the root password to djg345.
mysqladmin -uroot -pab12 password djg345

3. Add new users. (Note: Unlike the above, the following are commands in the MYSQL environment, so they are followed by a semicolon as the command terminator)
Format: grant select on database.* to username@login host identified by "password"
Example 1: Add a user test1 with the password abc, so that he can log in on any host and have query, insert, modify, and delete permissions on all databases. First connect to MYSQL as the root user, and then type the following command:
grant select,insert,update,delete on *.* to test1@"%" Identified by "abc";
But the added users in Example 1 are very dangerous , if you want someone to know the password of test1, then he can log in to your mysql database on any computer on the Internet and do whatever he wants with your data. See Example 2 for the solution.
Example 2: Add a user test2 with the password abc, so that he can only log in on localhost, and can query, insert, modify, and delete the database mydb (localhost refers to the local host, that is, the host where the MYSQL database is located) ), so that even if the user knows the password of test2, he cannot directly access the database from the Internet, and can only access it through the web page on the MYSQL host.
grant select,insert,update,delete on mydb.* to test2@localhost identified by "abc";
If you don’t want test2 to have a password, you can type another command to eliminate the password.
grant select,insert,update,delete on mydb.* to test2@localhost identified by "";

In the previous article we talked about login, adding users, password changes and other issues. In the next article, we will take a look at the database operations in MYSQL. Note: You must first log in to MYSQL. The following operations are performed at the MYSQL prompt, and each command ends with a semicolon.

1. Operation skills
1. If you forget to add a semicolon after pressing Enter when typing a command, you don’t need to type the command again, just type a semicolon and press Enter. In other words, you can divide a complete command into several lines and use a semicolon as the end mark.
2. You can use the cursor up and down keys to call up previous commands. But an old version of MYSQL that I used before does not support it. I am currently using mysql-3.23.27-beta-win.

2. Display command
1. Display the database list.
show databases;
There were only two databases at the beginning: mysql and test. The mysql library is very important. It contains MYSQL system information. When we change passwords and add new users, we actually use this library for operations.

2. Display the data table in the library:
use mysql; //Open the library, it will be familiar to those who have learned FOXBASE
show tables;
3. Display the structure of the data table:
describe table name;
4. Create database:
create database database name;
5. Create table:
use database name;
create table table name (field setting list);
6. Delete database and table:
drop database database name;
drop table table name;
7. Clear the records in the table:
delete from table name;
8. Display the records in the table:
select * from table name;

3. An example of creating a database, creating a table and inserting data
drop database if exists school; //Delete if SCHOOL exists
create database school; //Create library SCHOOL
use school; //Open library SCHOOL
create table teacher //Create table TEACHER
(
id int(3) auto_increment not null primary key,
name char(10) not null,
address varchar(50) default 'Shenzhen',
year date
); //Create table End
//The following are the insertion fields
insert into teacher values('','glchengang','Shenzhen No. 1 Middle School','1976-10-10');
insert into teacher values('','jack',' Shenzhen No. 1 Middle School','1975-12-23');

Note: In the table under construction

(1) Set the ID to a numeric field with a length of 3: int(3) and let each record automatically add 1: auto_increment cannot be empty: not null and make it the primary field primary key

(2) Set NAME to a character field of length 10

(3) Set ADDRESS to a character field of length 50, and it is missing The provincial value is Shenzhen. What is the difference between varchar and char? I will have to wait for a future article to talk about it.

(4) Set YEAR as the date field.
You can also type the above command at the mysql prompt, but it is not convenient for debugging. You can write the above command as it is into a text file, assuming it is school.sql, then copy it to c:, enter the directory mysqlbin in DOS state, and then type the following command:
mysql -uroot -p password If successful, a blank row will be left without any display; if there is an error, there will be a prompt. (The above command has been debugged, you only need to remove the // comment to use it).

4. Transfer text data to the database
1. The format that text data should conform to: field data are separated by tab keys, and null values ​​are replaced by n.
Example:
3 rose Shenzhen No. 2 Middle School 1976-10 -10
4 mike Shenzhen No. 1 Middle School 1975-12-23
2. Data input command load data local infile "file name" into table table name;
Note: You'd better copy the file to the mysqlbin directory, and first Use the use command to find the library where the table is located.

5. Back up the database: (The command is executed in the mysqlbin directory of DOS)
mysqldump --opt school>school.bbb
Note: Back up the database school to the school.bbb file, school.bbb is a text file, the file name Take whatever you want, open it and see what new discoveries you will make.

Postscript: In fact, the operation of MYSQL database is similar to that of other SQL databases. You'd better find a book about SQL. I will only introduce some basic ones here. In fact, that’s all I know, haha. The best MYSQL tutorial is the "MYSQL Chinese Reference Manual" translated by "Yan Zi". It is not only free and available for download on every relevant website, but it is also the most authoritative. Unfortunately, it is not in chm format like "PHP4 Chinese Manual", which is not convenient when searching for function commands.