1. Introduction to databases and SQL

2. What is a database?  A database is an organized way of holding together pieces of information  A database refers to a collection of data and not the means by which it is stored  Software that is used to manage data in a database is known as a database-management system (DBMS)  In a relational database-management system (RDMS), data is stored as a number of different tables that are related to each other in some way

3. Flat file vs RDBMS  Data can also be stored in a huge flat table  Each row in a flat table contains all the information about a system for that record  The difference between a relational database over a flat table system is that large databases can be constructed from different tables which contain only info relevant to that table

4. Why choose MySQL?  MySQL is distributed as open source software under the GNU General Public License  It is free to use  There are commercial versions where you can purchase support  Even with commercial support, total cost of ownership is much less than competitors (Oracle, SQL Server)  MySQL is robust, powerful and scalable  MySQL has replication and clustering to guarantee 100% availability  Extensive user base and wide community support and adoption (Facebook, Google, Yahoo, Apple, Microsoft, even Oracle)  Majority of website databases run on MySQL  It is a desired skill by employers

5. What is SQL?  Structured Query Language (SQL)  It is a common way to retrieve and manage database information  SQL uses descriptive English keywords so most queries are easy to understand  MySQL implementation of SQL conforms to the ANSI SQL standards  We will be learning the basics of SQL and enough to build simple web applications  Extensive database design, transactions, stored procedures, triggers etc is beyond the scope of this course  Entire courses and major parts of degrees are devoted to database topics

6. Connecting to MySQL  Using the command line Open Applications ->Terminal Emulator in Linux Type: mysql –uroot –p [Press Enter] Enter password: tec319 [Press Enter]

7. Connecting to MySQL mysql –uusername –ppassword OR mysql --user=yourname --password Example mysql –user=root --password Enter password:tec319[Press Enter]

8. Executing commands

9.  To use a specific database mysql> \u databasename mysql> select * from user; Records are grouped together mysql> select * from user mysql> \G

10. Executing commands  Running a script  mysql> mysql –user=yourname --password dbname < script.sql  The above command will execute the sql code in the script.sql tag on the database called dbname.

11. GUI MySQL Editor  Go to http://localhost/phpMyAdmin in a browserhttp://localhost/phpMyAdmin  For user and password enter: roottec319

12. Basic SQL Syntax

13. The SELECT statement  Selecting specific columns  Syntax  Select columnName from Tablename; eg Select firstName from students;  Selecting multiple columns Select firstName, lastName from students;

14. Selecting all records  In order to retrieve all column values from a table, the * character is used  Select * from students;  Remember that the semicolon (;) is needed to terminate a sql query  Select * from courses;

15. Filtering and Sorting Data

16. Where Clause  Where is added to select statements to tell MySQL to filter the query results based on a given rule  Rules in a WHERE clause refer to data values returned by the query  Only rows that have values which meet the criteria in the rule are returned

17. Exact match  Syntax example Select firstName, lastName from students where lastName = ‘Smith’; Select firstName, lastName from students where lastName != ‘Smith’; Select product_name, product_description from products where product_id=3443;

18. Filtering on a range of values  Syntax example Select * from products where price <=9.99; Select last_name from customer_contacts where last_name > ‘G’;  String values should be surrounded in single quotes

19. Ordering results – Order By Clause  Sorting on a single column Select * from products order by price; Select first_name, last_name from customer_contacts where customer_code =‘DEFC’ order by last_name;

20. Sorting on multiple columns Select order_date, customer_code from orders order by order_date, customer_code;

21. Specifying sort order  The default sort order is ascending depending on the data type of column e.g Select * from products order by weight; is equivalent to Select * from products order by weight asc; If you would like to sort the weight in descending order you can use: Select * from products order by weight desc;

22. Retrieving Database information  Retrieve a list of Databases  Show databases;  Retrieve a list of tables  Show tables;  Show tables from company;  Here company is the database name  Retrieving a List of Columns  Show columns from products;