MYSQL for beginners

In the previous article, the user guide for MYSQL Beginners describes logon, user addition, and password change issues. Next, let's take a look at the database operations in MYSQL. Note: you must first log on to MYSQL. the following operations are performed at the MYSQL prompt and each command ends with a semicolon.

I. operation skills
1. if you forget the extra points after you press enter when making the command, you don't have to repeat the command. you just need to press a semicolon to press Enter. That is to say, you can divide a complete command into several lines, and then use a semicolon as the end sign to complete the operation.
2. you can use the cursor to bring up or down the previous commands. However, an old MYSQL version I used earlier does not support this feature. I am using a mysql-3.23.27-beta-win.

II. display commands
1. display the database list.
Show databases;
At the beginning, there were only two databases: mysql and test. The mysql database contains the MYSQL system information. we change the password and add new users to use this database for operations.
2. display the data tables in the database:
Use mysql; // open the database. if you have learned FOXBASE, you will not be unfamiliar with it.
Show tables;
3. display the data table structure:
Describe table name;
4. database creation:
Create database name;
5. create a table:
Use database name;
Create table name (field setting list );
6. delete databases and tables:
Drop database name;
Drop table name;
7. clear records in the table:
Delete from table name;
8. display records in the table:
Select * from table name;

3. an instance for creating a database, creating a table, and inserting data
Drop database if exists school; // delete if SCHOOL exists
Create database school; // create a database SCHOOL
Use school; // open the SCHOOL library
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
); // Table creation ends
// Insert fields as follows
Insert into teacher values ('', 'glengang ', 'Shenzhen Zhongyi', '2017-10-10 ');
Insert into teacher values ('', 'Jack', 'Shenzhen Zhongyi ', '2017-12-23 ');

Note: in the table in progress (1), set the ID to a numeric field of 3: int (3) and make it automatically add one: auto_increment for each record. it cannot be blank: not null and set it as the main field primary key (2) set NAME to the character field with a length of 10 (3) set ADDRESS to the character field with a length of 50, the default value is Shenzhen. What is the difference between varchar and char? it will only be discussed later. (4) set YEAR as the date field.
If you type the preceding command at the mysql prompt, debugging is not convenient. You can write the preceding command as is to a text file, assuming it is school. SQL, then copy it to c:, and enter the directory mysqlbin in DOS state, and then type the following command:
Mysql-uroot-p password <c: school. SQL
If it succeeds, no display is displayed for a blank row. if there is an error, a prompt is displayed. (The preceding command has been debugged. you only need to remove the // annotation to use it ).

4. transfer text data to the database
1. text data should conform to the format: field data is separated by the tab key, and the null value is replaced by n.
Example:
3 rose:
4 mike: Shenzhen No. 1,-12-23
2. data import command load data local infile "file name" into table name;
Note: You 'd better copy the file to the mysqlbin directory and use the use command to create the database where the table is located.

V. back up the database: (execute the command in the DOS mysqlbin directory)
Mysqldump -- opt school> school. bbb
Note: back up the database school to the school. bbb file. school. bbb is a text file with any file name. open it and you will find new discoveries.

Note: In fact, MYSQL's database operations are similar to those of other SQL databases. you 'd better read this SQL book. Here I will only introduce some basic things. In fact, I only understand these things. The best MYSQL tutorial is the MYSQL Chinese reference manual translated by Yan Zi. it is not only free to download from every related website, but also the most authoritative. It is a pity that the chm format is not like the "PHP4 Chinese Manual", and it is not convenient to search for function commands.