I use MySQL and trying to write a PHP script for my school project.
There is one table named lessons contains this columns:
-id
-lessonid.
-studentid
I also have two different tables for notes and announcements
announcements and notes tables contains these columns:
-id
-lessonid
-content
-createdtime
I need to order both announcements and notes from latest to oldest by createdtime but also need to show all lessons a student takes.
For example: A students takes maths and physics lessons. I need to display him/her both notes and announcements for both of physics and maths and all items should be ordered by date. (like a timeline.) And of course I will not show him/her the notes and announcements for chemistry lesson. Also it will be good if I can say it is note or announcement on the list.
Can you help me to write SQL and PHP code for that?
Thanks.
EDIT: This is where I have stuck:
I have combined two tables and ordered them by date. But can't combine them with the lessons a student take.
SELECT title, created, lessonid FROM (SELECT title, created, lessonid FROM notes UNION SELECT title, created, lessonid FROM announcements) as a ORDER BY created DESC
First of all, thanks for letting us know that this is for a school project - therefore I won't give you the answer. If it is in the project then your teacher should have given you the concepts to come up with a solution.
Your question is well put together and I can see how to solve it but ... It's your project so you need to have a crack at it and post what you come up with.
I will give you some hints to get you started.
You need a query to combine the announcements and notes table. Then you need to group the data by the lesson and join that to the students. This is all basic SQL.
Good luck. Post what you come up with.
I'll also, follow fellow posters advice, and not do the legwork for you. but won't let you go empty handed, so will give you the concept.
there is a thing called third normal form, we decide how many tables according to that concept, so if its a big database then separate table for first name and separate for last name, as many people share those among themselves, so saves space and redundancy etc. so one table for person has personid as primary, and has lastname foreign key to refer to last name table , we generally name it lastNameRef, similarly firstNameRef. so now, each person has lot of classes, and each class has lot of persons(students) in it. so this is a many-many relation - we create a allreference table to solve this many to many problem. so there is one table for classes which has class id as primary key, so now u create a all reference table which a recordId as primarykey, (just for namesake) and personRef(refers to personId in person table) and classref(refers to classId in class table) if one person has two classes, another entry with same personId but different class Id, at the end, you can query the name of person from person table, and name of class from class table and create join on their foreign keys but use all three tables, result is (JOHN MATH, JOHN SCIENCE) etc, same way you display all notes for john searching name in person table, and subject in class table,and notes in notes table
Related
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Many-to-many relationships examples
(5 answers)
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I'm doing a project for a music school and I have a table for students, a table for courses available and I was creating the table for teachers. My question is, how can i manage to "link" a teacher to a certain or more than one course, so that when the teacher logs in the admin page, he can only update and add information to the students that belong to the course/s that he is teaching.
My first thought was that I should have a field in the teachers table that could only contain values from the courseID (for example, if i want to register a guitar teacher and the ID of the guitar course is 3, i should have a field in the teachers table named teacher_course_id which would have the value 3).I also thought about having more than one teacher for a course, and if so, how can I give permissions to one teacher only (the teacher of that student) and not all the teachers from that especific course?
I don't really need the code for anything, I just wanted a a brief explanation on how could I do it. If I wasn't clear enough I can give more details in the comments
You need one more table for relation between teachers and courses, smth like that:
course
id
title
...
teacher
id
name
...
teacher_course
course_id
teacher_id
can_edit 0/1
...
You can create table with fields teacher_id, course_id with Primary Key (teacher_id, course_id)
So my question is very much just a database design question. I'm relatively new to PHP, taking my first database course, and I'm trying to figure out how best to execute my idea.
So I'm building a membership database. Within this database there are "members" and there are "meetings," represented as two separate tables. I'm wondering what might be the best way to add a list of members to a meeting instance, or create a relationship table between the two. For example, would you advise that each member ID (primary key) be added individually (say, via a bunch of text input form fields) when creating a new meeting instance? Or perhaps is there a way to easily have the user upload a CSV or excel file of primary key user id numbers and, from those user number ids, easily create a relationship table?
Hope this is clear- just hoping to get some advice/insight, perhaps I'm not aware of the easiest way... Thanks!
I don't know what are you trying to do in your particular case, but is sounds to me that you should have three tables:
members - you have that one already
meetings - you also have that one already
members_meetings: this one is the table, that will join the two tables. And the required fields in that table should be:
member_id - the id of particular member, points to the id field in your members table
meeting_id - the id of the meeting, this member is attending, points to the id field in the meetings table
Than, if you want to get all members, that are attending meating X, you can just run the following query:
SELECT members.* FROM members_meetings LEFT JOIN members ON members_meetings.member_id = members.id WHERE members_meetings.meeting_id=X
I came up with this database design after discussing it with many people over IRC.
In my project, a User aka Member can have many "Teams" & "Projects" on his account and can be part of some "Projects" as well. Moreover, "Teams" can have many "Members" as well including the Member who is creating it.
Now my question is, suppose, a Member wants to create a Project or a Team under his account (later on I want to see all projects created by a specific member), can I do a insert into the using following in PHP?
INSERT INTO projects VALUES(values) WHERE member_id = something
I can get the member_id using the session variable I guess.
Use regular INSERT to create the projects or teams row, then use the ID created there to insert into the projects_members or teams_members. Also settle on plural or singular names for your tables (currently you have team not teams).
Your query would be somethings like this
Insert into
table(columns)
select (columns) from
another_table
where
conditions=.
Just Remember One thing the order and names of columns must match.
If Member wants to create a Project or a Team under his account it will not be possible using current structure.
You need to add one more column created_by on projects and team tables.
The name of "team" table should be "teams".
I am not necessarily looking for MySQL or PHP code. Rather I'm trying to get a concept of how to set everything up.
I want to create a database using MySQL (and using PHP to update it) of all the books my family owns. I want to set up different 'bookshelves' for each person in my family so we can see who has a certain book.
My first thought was to have a table for all the titles, authors, etc and have a field for user id to show who had the book. However, I might have a copy of Hunger Games and my grandmother might have a copy of Hunger Games. I want to be able to show it on both bookshelves. The only way my idea would work is if we had no duplicate books.
My next idea was to use a different table for each user and have a field that contains the book id for each book the user owns. I think this would work on a small scale but it does not seem like an efficient design. I am planning on making the database public for everyone in my town to use (thousands of people) once I get a stable website going so I want to start off with the right kind of design.
How should this be designed?
BOOK
--------
book_id
title
other_book_related_info
PERSON
-------
person_id
name
other_person_info
BOOK_PERSON
-------------
book_id
person_id
possibly-dates-when-this-person-owned-this-book
Here is one simple solution i can think of:
Book Table : List of all unique books
User Books : contains the user id and the book id. multiple users can own the same title.
Users : List of users;
This is pretty basic. Owner, book and author should be self explanatory. Add any additional fields to those tables you want. The bookshelf and book_authors are both cross reference tables so each book can have multiple owners and each book can have multiple authors.
**owner:**
owner_id
owner_name
...
**book:**
book_id
book_name
...
**author:**
author_id
author_name
...
**bookshelf:**
owner_id
book_id
**book_authors:**
book_id
author_id
You might like to differentiate between ownership of the book and current possession, since people will doubtless be borrowing. So the tables of BOOK (best call it ITEM if you're going to expand to DVD's etc) and PERSON, and the ownership table BOOK/MEDIA_OWNER, might be usefully accompanied by an ITEM_LOAN table.
You might like to also allow grouping of sets of items so that multiple volumes of a book, or discs of a show season, can be identified individually. Books (and films etc) also come in series, so think about how to represent that as well.
By the way, it's a generally accepted rule that if an edition of a work changes by more than 20% between print runs then it is a new impression, but it is not always granted a new ISBN. Depends on the publisher. Also, the hierarchy for books is based on Work -< Edition -< Impression, and these folks would be a good source of information of data structures relating to books.
Here's another solution:
**** BOOK ***
book_id
book_title
book_desc
book_bought
*** USERS ***
user_id,
name,
dateOfBirth
** Copies **
copy_id (PK)
user_id (FK)
book_id (FK)
NoOfCopies
I have two tables that look as Follows:
Person (Table Name)
Name1/Phone1/Email1/Address1/Organization1/Notes1 (Fields)
Organization (Table Name)
Organization1/Phone2/Email2/Address2/Web2/Notes2 (Fields)
Organization1 is the only field in common between the two tables.
When I display data on a person, I want to also check and see if there is data on their organization and display it as well if it exists. I'm using PHP to interface with mySQL.
You need to JOIN the tables.
SELECT * FROM Person LEFT JOIN Organization ON Person.Organization = Organization.Name;
This assumes the relationship is the Organization Name. I've done a LEFT JOIN since you said if exists. Check out this tutorial for more detail on joining tables.
Note: I agree and would recommend making your database more relational by adding Primary Keys and using them as Foreign Keys in your other tables.
This post is an explanation of relations, not code for you to use. If you want that, look elsewhere
Well, connections between tables are called relations. There are 3 types of relations.
1) One -> One - This type of relation means 1 row is related to 1 other row in a different table
2) One -> Many - This type of relation means 1 row is related to a variable number of rows in a different table.
An example may be A folder can have multiple files, but a file can't have multiple folders. So in this case the 1 would be the folder, and the many would be the files.
3) Many -> Many - This type of relation means many rows can relate to many other rows.
An example may be labels. You can label many things the same name (desk appliance for example), and each thing can have multiple labels (a lamp can have both desk appliance & light labels).
.
So now that you know the different relations, we will go into your question. The relation you are looking at is a one to many, one corporation can have many people, but a person can only have one corporation. I suppose a person could work for multiple people, but that is much more complex (so we'll skip it).
One to many relations are by far the most common, and are pretty easy to do. This is where joins come in (left, right, and inner joins). Tizag has an excellent tutorial on joins here: http://www.tizag.com/sqlTutorial/sqljoin.php.
Hope that helps.
You should use a foreign key, but you need to use the InnoDB storage engine (MyISAM does not support foreign keys yet).
Make your tables look something like this:
Person_ID, Name, Phone, Email, Address, Organisation_ID, Notes (or if you have multiple notes, create a seperate table that maps person_id to a note).
Organisation_ID, Name, Phone, Email, Address, Web, Notes.
Select your person, then if Organisation_ID exists, select the Organisation where Organisation_ID equals the ID you obtained from the person row.