04-SQL Data Management
27
4. SQL Data Management
description
SQL Data ManagementLPIC 1 - Linux Professional Institute
Transcript of 04-SQL Data Management
-
4. SQL Data Management
-
Structured Query Language
Used for retrieving/modifying data stored in a database
ANSI Standard but the devils in the details (proprietary
extensions)
-
MySQL Owned by Oracle, released under GPL
Also has a commercial version (Enterprise Server)
Used by Wikipedia, Google (for AdWords), and Facebook
PostgreSQL Open-source, MIT-style license
Community developed
Used by Yahoo (2PB of data!), MySpace, hi5, reddit
SQLite Library, not standalone DBMS
-
Information is stored in tables: Rows are objects (items)
Columns are attributes
Name Color Size Price
1 Mouse Blue 8x12cm $10
2 3G Modem White 4x8cm $50
3 Presenter Black 3x10cm $70
4 Phone Red 5x10cm $600
-
INTEGER (INT) 4-byte integer DECIMAL, NUMERIC exact precision (fixed-
point) numbers FLOAT, DOUBLE floating-point numbers DATETIME date and time CHAR fixed maximum length string VARCHAR variable length string ENUM enumerated list SET a set of zero or more values
-
Depending on the installation, you may need to authenticate The MySQL root user is different from the Linux root
user, and has a different password! (set at installation time)
MySQL commands are case insensitive
$ mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
[]
mysql>
-
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| mysql |
| wordpress |
+--------------------+
2 rows in set (0.00 sec)
mysql> use mysql;
[]
Database changed
-
mysql> show tables;
+---------------------------+
| Tables_in_mysql |
+---------------------------+
| columns_priv |
| db |
| func |
[]
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+---------------------------+
17 rows in set (0.00 sec)
-
mysql> describe db;
+-----------------------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------------+---------------+------+-----+---------+-------+
| Host | char(60) | NO | PRI | | |
| Db | char(64) | NO | PRI | | |
| User | char(16) | NO | PRI | | |
| Select_priv | enum('N','Y') | NO | | N | |
| Insert_priv | enum('N','Y') | NO | | N | |
[] | Execute_priv | enum('N','Y') | NO | | N | |
| Event_priv | enum('N','Y') | NO | | N | |
| Trigger_priv | enum('N','Y') | NO | | N | |
+-----------------------+---------------+------+-----+---------+-------+
22 rows in set (0.00 sec)
-
mysql> CREATE DATABASE test;
Query OK, 1 row affected (0.05 sec)
mysql> USE test;
Database changed
mysql> CREATE TABLE items (name VARCHAR(20), price DECIMAL(5,2));
Query OK, 0 rows affected (0.02 sec)
mysql> SHOW TABLES;
+----------------+
| Tables_in_test |
+----------------+
| items |
+----------------+
1 row in set (0.00 sec)
-
mysql> INSERT INTO items VALUES ('3G Modem', '50');
Query OK, 1 row affected (0.00 sec)
mysql> SELECT * FROM items;
+----------+-------+
| name | price |
+----------+-------+
| 3G Modem | 50.00 |
+----------+-------+
1 row in set (0.00 sec)
-
mysql> UPDATE items SET price='49.99' WHERE name= '3G Modem';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM items;
+----------+-------+
| name | price |
+----------+-------+
| 3G Modem | 49.99 |
+----------+-------+
1 row in set (0.00 sec)
-
mysql> SELECT * FROM items;
+----------+-------+
| name | price |
+----------+-------+
| 3G Modem | 49.99 |
+----------+-------+
1 row in set (0.00 sec)
mysql> SELECT name, price FROM items;
+----------+-------+
| name | price |
+----------+-------+
| 3G Modem | 49.99 |
+----------+-------+
1 row in set (0.00 sec)
-
mysql> SELECT * FROM items;
+----------+-------+
| name | price |
+----------+-------+
| 3G Modem | 49.99 |
| Mouse | 3.99 |
+----------+-------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM items WHERE price>10;
+----------+-------+
| name | price |
+----------+-------+
| 3G Modem | 49.99 |
+----------+-------+
1 row in set (0.00 sec)
-
mysql> SELECT items.name, items.price,
stocks.quantity
-> FROM items, stocks
-> WHERE items.name=stocks.name;
+----------+-------+----------+
| name | price | quantity |
+----------+-------+----------+
| 3G Modem | 49.99 | 10 |
| Mouse | 3.99 | 50 |
+----------+-------+----------+
2 rows in set (0.00 sec)
-
mysql> SELECT items.name, items.price, stocks.quantity
-> FROM items
-> JOIN stocks
-> ON items.name=stocks.name;
+----------+-------+----------+
| name | price | quantity |
+----------+-------+----------+
| 3G Modem | 49.99 | 10 |
| Mouse | 3.99 | 50 |
+----------+-------+----------+
2 rows in set (0.00 sec)
-
mysql> DELETE FROM items WHERE price SELECT * FROM items;
+----------+-------+
| name | price |
+----------+-------+
| 3G Modem | 49.99 |
+----------+-------+
1 row in set (0.00 sec)
-
mysql> DROP TABLE items;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW tables;
+----------------+
| Tables_in_test |
+----------------+
| stocks |
+----------------+
1 row in set (0.00 sec)
mysql> DROP DATABASE test;
Query OK, 1 row affected (0.04 sec)
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| mysql |
| wordpress |
+--------------------+
2 rows in set (0.00 sec)
-
MySQL users and passwords
Granting privileges
Backing up and restoring a database
-
Changing the root password:
user@vm-ubuntu:~$ mysqladmin -u root -p
password '123'
Enter password:
user@vm-ubuntu:~$
-
Creating a user:
user@vm-ubuntu:~$ mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
mysql> CREATE USER "user2"@"localhost" IDENTIFIED BY
"pass2";
Query OK, 0 rows affected (0.00 sec)
-
Granting permissions:
mysql> GRANT select,update,insert on mysql.* TO user2@localhost;
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT ALL PRIVILEGES on wordpress.* TO user2@localhost;
Query OK, 0 rows affected (0.00 sec)
-
user@vm-ubuntu:~$ mysqldump -u root -p mysql >
mysql.backup.sql
Enter password:
user@vm-ubuntu:~$
-
user@vm-ubuntu:~$ mysql -u root -p mysql <
mysql.backup.sql
Enter password:
user@vm-ubuntu:~$
