1, iSCSI technology introduced
Hard drive is an important part of computer hardware equipment, the speed of hard disk storage devices read and write speed can also affect the overall performance of the server.
In order to further enhance the performance of hard disk read and write speeds and storage devices, people have been working to improve the physical hard disk interface protocol devices. The current hard drive interface types are IDE, SCSI and SATA these three.
IDE is a mature and stable, inexpensive parallel transmission interface.
SATA is a transmission faster, more complete data check serial transmission interface.
SCSI is a standard for system-level generic interface between the computer and a hard disk device, optical drives and the like, having a system resource occupancy rate, high speed, transmission speed and so on.
2, MariaDB database
2.1) by (insert), delete (delete), change (update), check (select) all the sql statements must ";" No End
mysql -u root -p // use (Login) mysql
SET password = PASSWORD ( 'password'); // change the root password
CREATE USER user @ host IDENTIFIED BY 'password'; // create a database account management
use mysql; // use (operation) MySQL database
CREATE TABLE user (name char (10), phone int); // create a user table
INSERT INTO user (name, phone) VALUES ( 'user1', '13000000000'); // inserted into a user data table
SELECT * FROM user; // query the user table all the data
UPDATE user SET phone = 15000000000 [WHERE name = 'user1']; // modify the user table all the data field value phone 15000000000, [user1 will only change the name of the user phone field]
DELETE FROM user [WHERE name = 'user1']; // delete all the data in the user table, [delete only the user name of user1]
2.2) common formats and explain commands GRANT
| command | effect |
| GRANT privileges ON database form name TO username @ hostname | Give authorization for a particular database in a particular form |
| GRANT privileges ON database. * TO username @ hostname | Give authorization for all forms of a particular database |
| GRANT privileges ON *. * TO username @ hostname | The authorization given to all databases and all forms |
| GRANT privilege 1, 2 ON permissions database. * TO username @ hostname | Give more grants for all form a database |
| GRANT ALL PRIVILEGES ON *. * TO username @ hostname | All authorization given to all databases and all forms (need to be cautious operation) |
2.3) and the parameters used in the command action where
| parameter | effect |
| = | equal |
| <> Or! = | not equal |
| > | more than the |
| < | Less than |
| >= | greater than or equal to |
| <= | less than or equal to |
| BETWEEN | Within a certain range |
| LIKE | An example of search |
| IN | Search multiple values in a column |
