Summary of basic knowledge of mysql-Mysql Tutorial-php.cn

This article brings you a summary of the basic knowledge of mysql. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

1. Startup and Exit

1. Enter MySQL:

Start MySQL Command Line Client (MySQL DOS interface), directly Just enter the password you used during installation. The prompt at this time is: mysql>

or open the terminal and enter the SQL statement:

mysql –uroot –p123

2. Exit MySQL:

quit or exit

2. Library operations

1. Create database

Command: create database
For example : Create a database named xhkdb
mysql> create database xhkdb;

2. Display all databases

Command: show databases (note: there is an s at the end)
mysql> show databases;

3. Delete database
Command: drop database
For example: delete the database named xhkdb
mysql> drop database xhkdb;

4. Connect to the database
Command: use
For example: if the xhkdb database exists, try to access it:
mysql> use xhkdb;
Screen prompt: Database changed

5. The currently selected (connected) database
mysql> select database();

6. The table information contained in the current database:
mysql> show tables; ( Note: there is an s at the end

3. Table operation, you should connect to a database before the operation
1. Create table
Command: create table

[,.. ]);

mysql> create table MyClass(
> id int(4) not null primary key auto_increment,
> name char(20) not null,
> sex int(4) not null default &#39;0&#39;,
> degree double(16,2));

Copy after login

2. Get table structure
command : desc table name, or show columns from table name

mysql> desc MyClass;
mysql> show columns from MyClass;

Copy after login

3. Delete table
Command: drop table

For example: delete the table named MyClass
mysql> drop table MyClass;

4. Insert data
Command: insert into

[( [,..For example, insert two records into the table MyClass. These two records represent: the score of Tom named No. 1 is 96.45, and the score of Tom No. 2 is 96.45. The score of Joan, numbered 3, is 82.99, and the score of Wang, numbered 3, is 96.5.

mysql> insert into MyClass values(1,&#39;Tom&#39;,96.45),(2,&#39;Joan&#39;,82.99), (2,&#39;Wang&#39;, 96.59);

Copy after login

5. Query the data in the table
1), Query all rows
command : select from < table name> where < expression>
For example: view all data in table MyClass
mysql> select * from MyClass;
2), Query the first few rows of data
For example: View the first 2 rows of data in the table MyClass
mysql> select * from MyClass order by id limit 0,2;

6. Delete Data in the table
Command: delete from table name where expression
For example: delete the record numbered 1 in the table MyClass
mysql> delete from MyClass where id=1;

7, Modify the data in the table:
update table name set field = new value,... where condition
mysql> update MyClass set name='Mary' where id=1;

8. Add to the table Field:
Command: alter table table name add field type other;
For example: a field passtest is added to the table MyClass, the type is int(4), the default value is 0
mysql> alter table MyClass add passtest int(4) default '0'

9. Change the table name:
Command: rename table original table name to new table name;
For example: change the name of table MyClass to YouClass
mysql> rename table MyClass to YouClass;
Update field content
update table name set field name = new content
update table name set field name = replace(field name,'old content','new Content');
Add 4 spaces in front of the article
update article set content=concat(' ',content);

4. Introduction to field types
1 ． INT[(M)] type: normal size integer type
2． DOUBLE[(M,D)] [ZEROFILL] type: Normal size (double precision) floating point number type
3. DATE date type: The supported range is 1000-01-01 to 9999-12-31. MySQL displays DATE values in YYYY-MM-DD format, but allows you to use strings or numbers to assign values to DATE columns
4. CHAR(M) type: fixed-length string type. When stored, the right side is always filled with spaces to the specified length
5. BLOB TEXT type, the maximum length is 65535 (2^16-1) characters.
6. VARCHAR type: variable length string type

5. Database backup
1. Export the entire database
mysqldump -u username-p --default-character-set= latin1 database name> Exported file name (the default encoding of the database is latin1)
mysqldump -u wcnc -p smgp_apps_wcnc > wcnc.sql

2. Export a table
mysqldump -u user name -p database name table name> exported file name
mysqldump -u wcnc -p smgp_apps_wcnc users> wcnc_users.sql

3. Export a database structure
mysqldump -u wcnc -p -d – add-drop-table smgp_apps_wcnc >d:wcnc_db.sql
-d No data –add-drop-table Add a drop table before each create statement

4. Import database
Commonly used source commands
Enter the mysql database console,
For example, mysql -u root -p
mysql>use database
Then use the source command, the following parameters are Script file (such as the .sql used here)
mysql>source d:wcnc_db.sql

Related recommendations:

mysql basic knowledge ( mysql tutorial for newbies)

Summary of the basic knowledge of mysql

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mysql manual tutorial: //m.sbmmt.com/course/37.html

mysql video tutorial: http ://m.sbmmt.com/course/list/51.html

Related labels：

mysql php+mysql database

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