Coding Potpourri: MySQL
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This document discusses MySQL, an open source relational database management system. It provides examples of SQL commands for creating tables, inserting data, and querying tables. It also discusses common functions for joining tables, manipulating dates, strings, and numbers that are useful for reports. Popular websites that use MySQL are listed, and string, date, and math functions are highlighted as useful for statistics and manipulating data.
![Querying MySQL
• To query a single table you will structure your
query like this:
• SELECT column_names FROM table_name
[WHERE ...conditions] [ORDER
BY ...conditions];
• Statements in brackets are optional
• You can also select everything in a table by
using an * in place of column_names
Monday, July 25, 2011](https://image.slidesharecdn.com/aallmysql-110726083442-phpapp01/85/Coding-Potpourri-MySQL-7-320.jpg)
Coding Potpourri: MySQL
- 1. Coding Potpourri: MySQL Nicole C. Engard Director of Open Source Education, ByWater Solutions Author of Practical Open Source Software for Libraries Monday, July 25, 2011
- 2. My What? • MySQL: My Structured Query Language • Relational Database Management System • Licensed with the GNU GPL • That means it’s Open Source • Used to organize data in a structured way Monday, July 25, 2011
- 3. Who’s Using It? • MySQL is the database behind many popular web based applications • Wordpress • YouTube • Drupal • Flickr • Wikipedia • Ebay • Facebook • Google (not searches) Monday, July 25, 2011
- 4. Reading Table Structure CREATE TABLE `branches` ( `branchcode` varchar(10) NOT NULL default '', `branchname` mediumtext NOT NULL, `branchaddress1` mediumtext, `branchaddress2` mediumtext, `branchaddress3` mediumtext, `branchphone` mediumtext, `branchfax` mediumtext, `branchemail` mediumtext, UNIQUE KEY `branchcode` (`branchcode`) ) Monday, July 25, 2011
- 5. Reading Table Structure • This table’s name is ‘branches’ and it stores the information about libraries or branches in Koha. • Each field is easy to identify because of its name (ex. branchname is the library name). • A field with a number in parens after it is a field that is limited in size. • For example varchar(10) means the field can have no more than 10 characters in it • Lastly, we see that ‘branchcode’ is the unique key or unique identifier in the table. Monday, July 25, 2011
- 6. Inserting Data • Using the branches table enter a branch’s info INSERT INTO branches (branchcode, branchname, branchaddress1, branchaddress2, branchphone, branchemail) VALUES (‘LIB’, ‘My Library’, ‘123 Library Road’, ‘Philadelphia, PA’, ‘215.555.1234’, ‘info@library.com’); Monday, July 25, 2011
- 7. Querying MySQL • To query a single table you will structure your query like this: • SELECT column_names FROM table_name [WHERE ...conditions] [ORDER BY ...conditions]; • Statements in brackets are optional • You can also select everything in a table by using an * in place of column_names Monday, July 25, 2011
- 8. Querying MySQL • Using the branches table let’s query the data • This query will pull out only the Branch Names and Emails and put them in ascending order by name SELECT branchname, branchemail FROM branches ORDER BY branchname ASC; Monday, July 25, 2011
- 9. Querying MySQL • Using branches let’s get the address info from one specific branch SELECT branchname, branchaddress1, branchaddress2, branchaddress3, branchemail FROM branches WHERE branchcode=‘LIB’; Monday, July 25, 2011
- 10. Querying MySQL • Using branches let’s pull out the branch’s phone and fax in one column SELECT CONCAT(‘ph. ’, branchphone, ‘ fax ’, branchfax) as ‘contact info’ FROM branches WHERE branchcode= ‘LIB’; Monday, July 25, 2011
- 11. Another Table CREATE TABLE `issues` ( `borrowernumber` int(11) default NULL, `itemnumber` int(11) default NULL, `date_due` date default NULL, `branchcode` varchar(10) default NULL, `returndate` date default NULL, `return` varchar(4) default NULL, `renewals` tinyint(4) default NULL, `issuedate` date default NULL, KEY `issuesborridx` (`borrowernumber`), KEY `issuesitemidx` (`itemnumber`), ) Monday, July 25, 2011
- 12. Joining Tables • Using branches and issues let’s find out how many items circulated at each branch in a specific time period SELECT b.branchname, count(i.branchcode) as count FROM issues i LEFT JOIN branches b ON (i.branchcode=b.branchcode) WHERE i.issuedate BETWEEN ‘2011-06-01’ AND ‘2011-07-01’ GROUP BY b.branchcode ORDER BY count DESC; Monday, July 25, 2011
- 13. Date & Time Functions • The most common use for reports is for end of the month or end of the year statistics • The MySQL manual on Date & Time functions is essential for these queries • http://dev.mysql.com/doc/refman/5.6/en/ date-and-time-functions.html Monday, July 25, 2011
- 14. String Functions • Often you want to join two or more strings together, find a part of a string or even change a part of a string • String functions are defined in the MySQL manual • http://dev.mysql.com/doc/refman/5.6/en/ string-functions.html Monday, July 25, 2011
- 15. Math Functions • Using MySQL you can get fancy with statistics by using the number related functions • The Numeric Functions section of the manual can help you here • http://dev.mysql.com/doc/refman/5.6/en/ numeric-functions.html Monday, July 25, 2011
- 16. Common Functions • COUNT(FIELD) or SUM(FIELD) •Counts the number of or adds up the total value of results in a column • CURDATE() •Is the current date (not time, just date) • MONTH(FIELD) and YEAR(FIELD) •Return the month and year from a field • DATE_SUB(DATE, INTERVAL) •Subtract a period of time from a date Monday, July 25, 2011
- 17. Thank You Nicole C. Engard nengard@gmail.com Slides: web2learning.net > Publications & Presentations Monday, July 25, 2011