kernel_Notes/Zim/Programme/python/sql/mysql.txt

Content-Type: text/x-zim-wiki
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Creation-Date: 2011-10-17T00:43:21+08:00

====== mysql ======
Created Monday 17 October 2011

MySQL Tutorial: Install, Create DB and Table, Insert and Select Records

This MySQL jumpstart guide will get you running quickly on the basics. This explains how to install MySQL, create a sample database, create a table, insert records into the table, and select records from the table.

===== 1. Install and Configure MySQL =====

Go to the MySQL download page, and select your appropriate platform to download the latest version of MySQL community server.

* If you are installing on RedHat based distro (for example: CentOS), follow this article: Install MySQL on Linux using rpm
* You can also use yum groupinstall to install the MySQL Database group.
* If you want to install MySQL along with the other components of the LAMP stack (Apache, and PHP), follow this article: How to install or upgrade LAMP

===== 2. Create MySQL Database =====

Once MySQL is installed, connect to it using MySQL root user and create the database as shown below.

**# mysql -u root -p**
**Enter password:**
**mysql>**

After connecting as MySQL root user, execute the following command from the “mysql> ” prompt to create a database.

The following command will create the database called “thegeekstuff”.

**mysql> create database thegeekstuff**

Use “show databases” command to verify that the database was created successfully.

**mysql> show databases;**
**+--------------------+**
**| Database           |**
**+--------------------+**
**| information_schema |**
**| mysql              |**
**| thegeekstuff       |**
**+--------------------+**
**3 rows in set (0.00 sec)**


===== 3. Create MySQL Table =====

**Connect **to the newly created database using “use” command before you can perform any operation in the database.

To connect to the database, do the following.

**mysql> use thegeekstuff;**
**Database changed**

The following example creates a employee table.

**create table employee (**
**id INT AUTO_INCREMENT PRIMARY KEY,**
**name varchar(20),**
**dept varchar(10),**
**salary int(10)**
**)**__;__

When you copy-paste the above create table command in the “mysql> ” prompt, it will display the continuation prompt “->” starting from the 2nd line, which indicates that the command is still not over. The end of a SQL command is identified by a **semi-colon**.

**mysql> create table employee (**
**    -> id INT AUTO_INCREMENT PRIMARY KEY,**
**    -> name varchar(20),**
**    -> dept varchar(10),**
**    -> salary int(10)**
**    -> );**
**Query OK, 0 rows affected (0.00 sec)**

You can also use any one of the following data types.

* dcode** SMALLINT**
* mcode **MEDIUMIN**
* project_start **DATE**
* loggedon** TIME**

Do the following to view all the tables available in the database.

**mysql> show tables;**
**+------------------------+**
**| Tables_in_the geekstuff |**
**+------------------------+**
**| employee               |**
**+------------------------+**
**1 row in set (0.00 sec)**

To view the table //description,// do the following.

**mysql> desc employee;**
**+--------+-------------+------+-----+---------+----------------+**
**| Field  | Type        | Null | Key | Default | Extra          |**
**+--------+-------------+------+-----+---------+----------------+**
**| id     | int(11)     | NO   | PRI | NULL    | auto_increment |**
**| name   | varchar(20) | YES  |     | NULL    |                |**
**| dept   | varchar(10) | YES  |     | NULL    |                |**
**| salary | int(10)     | YES  |     | NULL    |                |**
**+--------+-------------+------+-----+---------+----------------+**
**4 rows in set (0.01 sec)**

===== 4. Insert Records into a Table =====

Use the following sample insert commands to insert some records to the employee table. While inserting values to //all //the columns in the table, you don’t need to specify the column name. Just specify the values in the same sequence as the column names.

**insert into employee values(100,'Thomas','Sales',5000);**
**insert into employee values(200,'Jason','Technology',5500);**
**insert into employee values(300,'Mayla','Technology',7000);**
**insert into employee values(400,'Nisha','Marketing',9500);**
**insert into employee values(500,'Randy','Technology',6000);**

To insert values only to specific columns, you should specify the// column names //as shown below.

**mysql> insert into employee(name,dept) values('Ritu', 'Accounting');**
**Query OK, 1 row affected (0.01 sec)**

Note: You can also upload data from a text file to MySQL database using **mysqlimport **command.

===== 5. Query Records from a Table =====

To view all the records from a table, use the following select statement.
http://www.thegeekstuff.com/2011/10/mysql-tutorial-basics/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+TheGeekStuff+%28The+Geek+Stuff%29
**mysql> select * from employee;**
**+-----+--------+------------+--------+**
**| id  | name   | dept       | salary |**
**+-----+--------+------------+--------+**
**| 100 | Thomas | Sales      |   5000 |**
**| 200 | Jason  | Technology |   5500 |**
**| 300 | Mayla  | Technology |   7000 |**
**| 400 | Nisha  | Marketing  |   9500 |**
**| 500 | Randy  | Technology |   6000 |**
**| 501 | Ritu   | Accounting |   NULL |**
**+-----+--------+------------+--------+**
**6 rows in set (0.00 sec)**

To view only a specific columns from a table, specify the column names in the select command.

**mysql>  select name, dept from employee;**

The following select statement has a where condition which displays the employee records who belong to Technology department and getting a salary >= 7000.

**mysql> select * from employee where dept = 'Technology' and salary >= 6000;**
**+-----+--------+------------+--------+**
**| id  | name   | dept       | salary |**
**+-----+--------+------------+--------+**
**| 300 | Mayla  | Technology |   7000 |**
**| 500 | Randy  | Technology |   6000 |**
**+-----+--------+------------+--------+**
**2 rows in set (0.00 sec)**