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".
Related
I have 4 tables in my DB:
Table project_ppi:
id (PRIMARY KEY)
Table scopus_author:
id (PRIMARY KEY),
project_ppi, -> linked to id in table project_ppi
author_scopus_id
Table author_subject_area:
author_id (PRIMARY KEY) -> linked to id in table scopus_author
Table project_author_match:
project_ppi (PRIMARY_KEY),
author_scopus_id (PRIMARY KEY),
match_value
What I need to do:
In practice, given a project (table project_ppi) I need to show all the authors (table scopus_author) linked to this project and for each author show his/her area of working (table author_subject_area) but order the result by match_value (table project_author_match).
I'm able to do it in "normal SQL" statements but I'm stuck in doing it in Yii2 framework.
I have a model for each of these tables in my php but I don't really know where to start.
Can anyone give me a hint?
Thanks in advance!
In short
There are already a handful of guides that can help you, and stating that you use a normal SQL database; like MariaDB or MySQL therefore you ought to use ActiveRecord Models. More of details here (https://www.yiiframework.com/doc/guide/2.0/en/db-active-record)
A bit of details
As you should do, you have models for each table, then in each model you add a method that is preferable to be called "getSomething" and this uses the "hasOne" or "hasMany" relation between tables, then in your Yii query you just use the joinWith('relationName') method will making your query. An example:
$query = Post::find()->joinWith('user')->where(['user.id' => 1]);
And this query will get all posts that were written by user whose ID is 1. Assuming a simple database with 2 tables user, post
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 want to create a posting system to a profile. I created a database for storing all users posts each user have a table.
Ihad created another database for storing the comments of each posts. My logic is to create each table in the comments database and store each comment in that.
Is there a logic to link the post and the comments. I thought to use mysql last insert id but it will return last id which will create error because one of the post will not have a table.
Is there any other way?
Another way would be to have a single table for posts, and identify a user post in the table using a userid column. To find all posts by a particular user, simply query by the user's ID. By doing so, you have a single table to manage, and you can do a lookup easily. If you create separate tables for each user, you have to create additional logic to first figure out which table to use. If a user is removed, you delete a table, rather than simply removing some rows from a common table.
The same logic applies to the comments table - add columns for postid',commentid,userid`. Again, a single table contains all the comments. To find comments on a particular post, you would do a simple query such as
select comment_text
from comments_table
where postid = ?
The whole purpose of using MySQL is to leverage relationships between entities, i.e. a user owns posts, a post is linked to comments.
If you do not want to use a relational schema like this, take a look at NoSQL DBs.
You have a couple options here:
Add a user_id column to your posts table, and a post_id, and user_id column to your comments table. You can then setup foreign keys with one-to-many relationships.
Only use a single table that has (in addition to your existing) a user_id, and type column. Type will define comment/post/etc. This can be defined with intermediary tables as a number mapped to a CONST, string, or any other way that you see fit (intermediary best option imho).
Vary the above example and use 2 intermediary tables to match users to posts and comments to posts (possibly also users to comments).
I've done quit a bit of programming with php/mysql on small scale personal projects. However I'm working on my first commercial app that is going to allow customers or businesses to log in and perform CRUD operations. I feel like a total noob asking this question but I have never had to do this before and cannot find any relevant information on the net.
Basically, I've created this app and have a role based system set up on my data base. The problem that I'm running into is how to separate and fetch data for the relevant businesses or groups.
I can't, for example, set my queries up like this: get all records from example table where user id = user id, because that will only return data for that user and not all of the other users that are related to that business. I need a way to get all records that where created by users of a particular business.
I'm thinking that maybe the business should have an id and I should form my queries like this: get all records from example where business id = business id. But I'm not even sure if that's a good approach.
Is there a best practice or a convention for this sort data storing/fetching and grouping?
Note:Security is a huge issue here because I'm storing legal data.
Also, I'm using the latest version of laravel 4 if that's any relevance.
I would like to hear peoples thoughts on this that have encountered this sort problem before and how they designed there database and queries to only get and store data related to that particular business.
Edit: I like to read and learn but cannot find any useful information on this topic - maybe I'm not using the correct search terms. So If you know of any good links pertaining to this topic, please post them too.
If I understand correctly, a business is defined within your system as a "group of users", and your whole system references data belonging to users as opposed to data belonging to a business. You are looking to reference data that belongs to all users who belong to a particular business. In this case, the best and most extensible way to do this would be to create two more tables to contain businesses and business-user relations.
For example, consider you have the following tables:
business => Defines a business entity
id (primary)
name
Entry: id=4, name=CompanyCorp
user => Defines each user in the system
id (primary)
name
Entry: id=1, name=Geoff
Entry: id=2, name=Jane
business_user => Links a user to a particular business
user_id (primary)
business_id (primary)
Entry: user_id=1, business_id=4
Entry: user_id=2, business_id=4
Basically, the business_user table defines relationships. For example, Geoff is related to CompanyCorp, so a row exists in the table that matches their id's together. This is called a relational database model, and is an important concept to understand in the world of database development. You can even allow a user to belong to multiple different companies.
To find all the names of users and their company's name, where their company's id = 4...
SELECT `user`.`name` as `username`, `business`.`name` as `businessname` FROM `business_user` LEFT JOIN `user` ON (`user`.`id` = `business_user`.`user_id`) LEFT JOIN `business` ON (`business`.`id` = `business_user`.`business_id`) WHERE `business_user`.`business_id` = 4;
Results would be:
username businessname
-> Geoff CompanyCorp
-> Jane CompanyCorp
I hope this helps!
===============================================================
Addendum regarding "cases" per your response in the comments.
You could create a new table for cases and then reference both business and user ids on separate columns in there, as the case would belong to both a user and a business, if that's all the functionality that you need.
Suppose though, exploring the idea of relational databases further, that you wanted multiple users to be assigned to a case, but you wanted one user to be elected as the "group leader", you could approach the problem as follows:
Create a table "case" to store the cases
Create a table "user_case" to store case-user relationships, just like in the business_user table.
Define the user_case table as follows:
user_case => Defines a user -> case relationship
user_id (primary)
case_id (primary)
role
Entry: user_id=1, case_id=1, role="leader"
Entry: user_id=2, case_id=1, role="subordinate"
You could even go further and define a table with definitions on what roles users can assume. Then, you might even change the user_case table to use a role_id instead which joins data from yet another role table.
It may sound like an ever-deepening schema of very small tables, but note that we've added an extra column to the user_case relational table. The bigger your application grows, the more your tables will grow laterally with more columns. Trust me, you do eventually stop adding new tables just for the sake of defining relations.
To give a brief example of how flexible this can be, with a role table, you could figure out all the roles that a given user (where user_id = 6) has by using a relatively short query like:
SELECT `role`.`name` FROM `role` RIGHT JOIN `user_case` ON (`user_case`.`role_id` = `role`.`id`) WHERE `user_case`.`user_id` = 6;
If you need more examples, please feel free to keep commenting.
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