creating databases
DESCRIPTION
Creating Databases. SELECT. UPDATE. Demonstrate projects. Classwork / Homework: Prepare for review for midterm. SELECT. … what if you want only DISTINCT values? - PowerPoint PPT PresentationTRANSCRIPT
Creating Databases
SELECT. UPDATE.
Demonstrate projects.
Classwork / Homework: Prepare to choose teams & projects.
Warning
• Changes in php from last time.– THIS IS INEVITABLE and is mainly a good
thing.
• I think I made required changes, but only did modest testing.– AND I did all the testing. Always involve other
people to do testing!
SELECT
• … what if you want only DISTINCT values?
• For example, the trivia quiz starts with a form to choose the category. People (site administrators) adding questions can put in any category.
• http://socialsoftware.purchase.edu/jeanine.meyer/quiz/choosecategory.php
from php code choosecategory.php
<h1> Welcome to the Quiz </h1> <br><h3> Sign in and select a category for your question </h3><form action="askquestion.php" method=post>
<p>Name <input type=text name='player' size=30<?php…
$query="SELECT DISTINCT category FROM questions";$categories = mysqli_query($link,$query);while ($row=mysqli_fetch_array($categories)){ $cat=$row['category']; print ("<option value='$cat'>$cat</option><br>\n");}
SQL join
• SELECT statement against a table made up by JOINing tables together on identical fields.
• Different types of JOIN:– JOIN (same as INNER JOIN)– LEFT JOIN– RIGHT JOIN– FULL JOINhttp://www.w3schools.com/sql/sql_join.asp
LEFT, RIGHT, FULL JOINs
• These provide ways to pick up missing records.
• CHECK OUT THE w3schools and other tutorials!
• Will show example from the quiz show– Task: find questions that player has NOT
answered correctly and has NOT been asked that day.
Two steps
• Create a temporary table of all the questions asked a particular player and answered correctly OR asked today.– need to specify the contents of the table. In
this case, one field of INT datatype
• If there have been past questions, do a SELECT using LEFT JOIN to extract any question NOT present in the past array. Otherwise, do a simple SELECT
$query="CREATE temporary TABLE past (item_id INT)";
$query.= " SELECT question_id FROM history WHERE (player_id='".$player_id;
$query.= "' AND (whenplayed='".$today."' OR correct))";
$result=mysqli_query($link,$query);$query="SELECT * FROM past";$result = mysqli_query($link,$query);$Num_past = mysqli_num_rows($result);
1st step: create temporary table, past
2nd step
if ($Num_past>0) { $sel = "SELECT questions.question_id, question,
answerpattern, value from questions"; $sel =$sel . " LEFT JOIN past ON questions.question_id =
past.question_id WHERE "; $sel = $sel . " category='" . $pickedcategory . "' AND
past.question_id IS NULL"; }else { $sel="SELECT question_id, question, answerpattern,
value from questions "; $sel= $sel . " WHERE category= '" . $pickedcategory. "'"; }
SELECT Conditions
• WHERE – Sets condition on individual records
• with a JOIN – the ON specifying what field to do the JOIN
on, generally a foreign key equal to a primary key
• After aggregating using GROUP– HAVING sets a condition on grouped data
Conditions
• Remember: the single equal sign is the operator for equality!
• Other comparisons: >, <, >=, <=
• LOGIC: AND, OR, NOT
• REGEX for regular expressions
• LIKE: another way to specify a pattern
Conditions
• Can select using set of values
• SELECT * FROM questions WHERE category IN (‘trivia’,’misc’,’silly’)
• See also BETWEEN
Recall
• 4 tables
movies
mid
mname
mdate
people
pid
pname
…
roles
rid
mid
pid
role (director,actor,etc.)
nominations
aid
rid
category
win
…
In most cases, peoplehave only 1 role. Affleck is an exception.In most cases, awards are for 1 role. Producingis an exception. Some roles are notnominated for anything,hence the 0.
0
Tasks• List all movies by name, ordered by date
– SELECT mname, mdate FROM movies ORDER BY mdate
• List all people by name with roles in a given movie, named $moviename (this is mixture of php and straight SQL)– SELECT p.pname,m.mname,r.role FROM
movies as m JOIN roles as r ON m.mid = r.mid JOIN people as p ON p.pid = r.ridWHERE m.mname='$moviename'
next task: reuse JOIN clauses
• List all directors (by name), with movie (by name) ordered by movie name– SELECT p.pname,m.mname FROM movies
as m JOIN roles as r ON m.mid = r.mid JOIN people as p ON p.pid = r.ridWHERE r.role='Director' ORDER BY m.mname
• List all movies by name in which someone was nominated for Best Lead Actor– SELECT m.mname FROM movies as m
JOIN roles as r ON m.mid = r.mid JOIN people as p ON p.pid = r.ridJOIN nominations as n ON n.rid=r.ridWHERE n.award='Best Lead Actor'
next task, again reuse JOIN clauses plus start of WHERE
• List all movies by name in which someone was nominated for an acting category. Count number.– Best Lead Actor, Best Lead Actress, Best Supporting
Actor, Best Supporting Actress– SELECT m.mname, count(*) FROM movies as m
JOIN roles as r ON m.mid = r.mid JOIN people as p ON p.pid = r.ridJOIN nominations as n ON n.rid=r.ridWHERE n.award IN ('Best Lead Actor, Best Lead Actress, Best Supporting Actor, Best Supporting Actress) ORDER BY m.mname GROUP BY m.mname
More
• List movie name, person name, nominated award ordered by movie name– SELECT m.mname, p.pname, n.award
FROM movies as m JOIN roles as r ON m.mid = r.mid JOIN people as p ON p.pid = r.ridJOIN nominations as n ON n.rid=r.rid ORDER BY m.mname
Next
• List winners: movie name, person name, award– SELECT m.mname, p.pname, n.award
FROM movies as m JOIN roles as r ON m.mid = r.mid JOIN people as p ON p.pid = r.ridJOIN nominations as n ON n.rid=r.rid ORDER BY m.mname WHERE n.win='true'
• List movie name, number of people nominated, ordered from high to low– SELECT m.mname, count(*) FROM movies as m
JOIN roles as r ON m.mid = r.mid JOIN people as p ON p.pid = r.ridJOIN nominations as n ON n.rid=r.rid ORDER BY m.mname GROUP BY m.mname
– EXTRA CREDIT: figure out how not to count multiples for awards that have multiples (such as producer, technical awards)
Research
• Some questions require consideration of absent records– What movies were nominated (had people
nominated) for Best Movie but not Best Director
– ?
• Look up and study examples of LEFT JOINS
UPDATE
• Can update a single record or a set of records.
• UPDATE questions SET text = ‘$ntext’ WHERE ques_id=‘$qid’– Assumes table names questions with fields
text and ques_id and php variables $ntext and $qid set previously
UPDATE
• Raise all the prices 10%– UPDATE products SET price=1.10*price
• Raise the prices that are over 100 by 5%– UPDATE products SET price=1.05*price
WHERE price > 100
Projects• Recall Geolocation / Google maps email.
http://socialsoftware.purchase.edu/jeanine.meyer/emailing/geolocationkmemail.html
• Quizhttp://faculty.purchase.edu/jeanine.meyer/html5/mapmediaquiz.html
• Does not use database. Enhancement is to add database for locations
Projects
• Bookmarks, with password system for finders
– http://socialsoftware.purchase.edu/jeanine.meyer/research/addsite.html
– http://socialsoftware.purchase.edu/jeanine.meyer/research/showsitesbycategory1.php
Projects
• Student departmentshttp://socialsoftware.purchase.edu/jeanine.meyer/studentexample/showstudents.php http://socialsoftware.purchase.edu/jeanine.meyer/studentexample/showdepartments.php http://socialsoftware.purchase.edu/jeanine.meyer/studentexample/enterstudent.html
Projects
• Trivia quizhttp://socialsoftware.purchase.edu/jeanine.meyer/quiz/choosecategory.php http://socialsoftware.purchase.edu/jeanine.meyer/quiz/inputquestions.php – edit feature?– change scoring?– improve interface?
Projects
• Origami storehttp://socialsoftware.purchase.edu/jeanine.meyer/orders/orderproduct.php
http://socialsoftware.purchase.edu/jeanine.meyer/orders/inputproducts.php need file upload to upload pictures
– general improvement– scale up
Projects• Songs and features in songs. Find similar
songshttp://socialsoftware.purchase.edu/jeanine.meyer/example/findothers1.php http://socialsoftware.purchase.edu/jeanine.meyer/example/addsong.html http://socialsoftware.purchase.edu/jeanine.meyer/example/addfeature.html http://socialsoftware.purchase.edu/jeanine.meyer/example/addfeaturestosong1.php
Stories
• http://socialsoftware.purchase.edu/jeanine.meyer/stories/tellStory.php
• http://socialsoftware.purchase.edu/jeanine.meyer/stories/enterscene.html
• http://socialsoftware.purchase.edu/jeanine.meyer/stories/addscene.php
• http://socialsoftware.purchase.edu/jeanine.meyer/stories/showAllScenesforediting.php
Citations
• http://socialsoftware.purchase.edu/jeanine.meyer/citations/drawlinksAsArrows.php
• http://socialsoftware.purchase.edu/jeanine.meyer/citations/inputjournals.php
• http://socialsoftware.purchase.edu/jeanine.meyer/citations/inputarticles.php
• http://socialsoftware.purchase.edu/jeanine.meyer/citations/addlink1.php
Assignment
• Team project to present and
• Enhance one of these projects
• There will be an assignment to build database project totally on your own
Projects• student database• trivia quiz• book marks• songs• origami store• Stories
• Google maps media portal (or quiz)– Note: this does NOT have a database at all! So obvious
enhancement is to make use of database, possibly with table for player or ???
• Late addition: citations (needs updating)
Preview (after midterm)
• Self assign or I assign teams (4-5)
• Teams will pick projects– resolve conflicts
Homework
• Prepare to form teams AND choose application.
• Working with existing code is…always a challenge but more common than starting from nothing.