I want to create a MySQL database for a project in which users can come and make comments on other profile. Every profile has a unique id to identify it, now when a user comes and makes comment on other profile I'll need to store the user id of the person who made the comment and the person on whose profile the comment was made, along with that I'll need to store the comment in the database.
As many users can make comments on a single profile, I'll need to store all the comments and the users who made them on a single profile. For this how many tables should I create and how many columns should they have? For this I'm thinking about creating a table for named user_comments and that has column user_id, commenter_id (all the commenter who commented their id separated by comma), comments (then all the user comments separated by comma).
Will this work?
For this I'm thinking about creating a table for named user_comments
and that has column user_id ,commenter_id(all the commenter who
commented their id seprated by comma) ,comments(then All the user
comments seprated by comma)
God no! You are almost there:
Table comments
id INT AUTO_INCREMENT
recipient_id
sender_id
message TEXT
[ sent DATETIME ]
[ other meta data ]
Store one message in message. Create one row per message. Never store several records in the same field separated by anything.
I'd have a profile_comment table:
id, text, profile_user_id, commenter_user_id, created_at
And a user table:
id, name, email
You can see here that the first table has two foreign keys to the user table - one points to the owner of the profile, and the other points to the owner of the comment. You can sort them in order of created_at to list them as you would on a blog, either in forward or reverse order.
Now, when you are rendering a profile page, you can get the profile id from your query string:
$profileId = isset( $_GET['profile_id'] ) ? $_GET['profile_id'] : null;
From there, you can add it into a SQL query:
SELECT * FROM profile_comment
WHERE profile_user_id = :profile_id
ORDER BY created_at
The colon mark here is a placeholder you can use with a parameterised query, which helps protect against SQL injection. However, you can build the statement as a string if you are careful to untaint any user input you insert into it.
Related
So I have a question, I'm hoping it isn't too subjective.
I have a blog-style website, so on the homepage articles are loaded alongside the date published, the user that posted it, etc. Basic data like this.
I store it in MySQL like so:
article_id username date content etc.
1 user1 2015-05-14 01:35:14 my content a
2 user2 2015-05-16 02:33:15 my content b
This way, I can display it using one query, where I retrieve the username, date, content, etc.
My question is. I want to allow users the option to change their username. There are two options I see for this.
Either I continue storing data as I do now, and manually update tables like this with user-related data to the new username. Or I store data by a user_id rather than username, and have an extra query for each article loaded to get the associated username from another user table.
Which is the correct approach?
I ask this because I assume there's a recommended practice for this situation? Is it normal to store data by username and update it, or to store by id to avoid having to do this - but at the cost of the overhead when querying data. I'm guessing it's possible to display the username for id-based data in just one query, but that would still take significantly longer?
Depends. Do you see there is a 1:1 relationship with Article:User if yes, then storing in a single table will probably suffice but generally an user will publish multiple articles which will make it a 1:* relationship and in which case you should create a separate table for UserDetailsd and have user_id as FOREIGN KEY in Article table probably.
You should create a users table, store user_id which would be incremental and a user_name. When showing the user name in your app, join to the users table and show the name from that table and it will always be current. This is the best practice if you wish to allow user name changes. Updating all usernames it the articles table is not recommended. This will also allow you to store other user related information such as email, join date, etc... without having to keep all that in the articles table.
Create a seperate table with all user-related information and alter your current table, so only content and article related stuff is included. That's what I'd suggest you
Make a separate table for users something like:
-------------------
user_id | user_name
-------------------
Where user_id should be PK.
And another table, lets say article should look like:
-----------------------------------------------
arcticle_id | date | content | etc. | user_id
-----------------------------------------------
Where article_id could be a PK and user_id would be the FK from users table, making a relationship which could be used in other tables as well.
You can create a table for users, and use a foreign key on field username, specifying the behavior on updates. Is something like this:
alter table posts add constraint fk_post_user foreign key (username) references users (name) on update cascade;
In this way, when you update a row on table users, all user names on table posts will be updated too.
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 have a database with employees. the columns are first name, last name, department, internal number etc..
As for today it is a database only for one organization but in future i want to add to this database employees from other relative organizations.
What is the right way to do it:
To add another field to the first table ?
To create another table with 3 fields: id, organization_name, employees ( where in this filed i would put comma separated values of id from first table) ?
if the second answer will be chosen what will happened when an update query will be executed simultaneously from different accounts to the same organization. For example: i will be adding a user with id 55 to organization 'Police' and at the same time another administrator will be adding to the same organization a user with id 65..
In this case is there a possibility of error or data-loss ???
If someone had this kind of problem before, i really would like to read about it..
Thank You..
If the organization is only a number to group the users, then I would suggest to put them into the employees table. However if you have more information about the organization (e.g. name, address .. ) then make a new table for the organization and save the primary key of the corresponding organization in the employees-table.
I have working website in PHP with a MySQL backend which has several tables for different purposes.
This site is based on different parts or 'environments' like a bugtracker, project management, etc.
There is one central 'users' database which has all the users with the associated details in them.
In each of previously mentioned 'environments', which all have their own set of tables, it is possible to specify a user ID in certain fields.
e.g. the bugtracker table has a column called AssignedTo which contains the user ID's of users to whom bugs have been assigned.
The field type of these 'user ID' columns (like the AssignedTo example) is the same as the UserId field in the central users table, which is an unsigned, zerofilled INT(5) field.
Now I have a request from the users of this site to also allow to specify user groups in certain of these user ID fields.
So again reffering to the AssignedTo example, it should now be possible to also assigned a bug to a user group, instead of a specific user.
What's the best way to do this regarding the PHP scripting and the database layout?
Now I have all these fields set to the same type as the UserId of the central users table, which is INT(5).
However my UserGroupId field in the UserGroups table, is of a different format, INT(3).
I could make this field also into an INT(5) field, but that would not solve the 2nd issue I'm having: how to see whether the AssignedTo value is reffering to a specific user, or to a usergroup.
I was thinking about make the UserGroupId field start from 99999 and counting downwards, while the UserId field is starting from 00001 and counting upwards, thus assuming that if the AssignedTo starts with 9, it's reffering to a usergroup.
But this doesn't seem like a clean solution to me...
Any better ideas?
Thanks!
I think I understand what you are trying to say. I have a question. Can a user be in multiple UserGroups?
I would probably add a column in the bug table that says whether the AssignedTo value refers to a UserID or a UserGroupID.
Create a separate table for UserGroups.
If Users can belong to multiple groups, create an association table like: AssociationID, UserID, UserGroupID.
Otherwise if each user can only belong to one group, just add a UserGroupID column to the Users table
If I am understanding correctly, my solution would be to instead of having an AssignedTo column pointing to either a user or a user group, I would create two columns. One pointing to the user id and another pointing to a user group id.
Actually a colleague at work came up with the following solution which I really like:
Change the UserId and UserGroupId field types from INT(5) to INT(4). And leave the different fields like AssignedTo set to INT(5).
Now in the PHP code I can add a prefix number to either the 'UserId' or 'UserGroupId' value, this prefix number can be used to determine if the value is reffering to a UserId or a UserGroupId value.
So if the AssignedTo field is '10005' it means it's a 'user' with 'id: 0005'. Also to prevent having to update all existing records, values which have a '0' at the first position will be considered users
The advantage over using positive/negative values here is that in both the Users and UserGroups tables I can still use a positive 'Id' field which can be left to autoincrement. As far as I know auto-incrementing is not possible with negative values
I already have a simple registration system in place using php and mysql. It operates well enough. However, when people visit my site and register, I would like for them to register as part of a particular group. So, I was thinking that registration would happen like this:
Visitor lands on index.php, clicks on "Group Registration" link.
Visitor supplies group name and group password. [A new table is created for that group where all user data will be stored for that particular group]
Visitor then is prompted for typical registration data--name, email, etc.--and that data is stored in the newly created group table.
Any subsequent visitors associated with that group would click on "User Reg"
The visitor would be prompted for group name and password
If correct, then he would be prompted for typical reg data, to be stored in his group's table.
What I don't know how to do is implement the group authentication prior to allowing user registration. Can someone help me with that?
If the visitor is entering a group name and password, then you can authenticate the same way you are doing the users. You just need to first ask yourself if the group name needs to be unique or the group/password combination.
As for your idea to add a new table for each group, that is a bad idea. Imagine if you have 100 groups. Then you will have 100 tables just for groups. If you get up to 1000 groups, then you will have 1000 tables. Try managing that. It will get really frustrating really fast. Instead, what you should do is to first create a "Group" table with all the associated data (group name, password, etc). Then add a field to your User table that will hold the associated id from the Group table. That way, whenever you look up the user, you can easily check what group the user is in simply by joining the two tables rather than trying to figure out what table to look at as in your original plan.
What you want to end up with is a table for your users and another (single) table for your group information. The user table will have a foreign key field to link it to a group. When a user joins a group, you will enter a value in that field. Users not in groups will have a null value in that field. If users can create groups, they will simply be adding a new row to the groups table.
If your users can be in multiple groups, set up your tables like this.
USER
- id
- username
- password
- etc...
GROUP
- id
- name
- password (?)
- etc...
USER_GROUP_CR
- fk_user
- fk_group
The USER_GROUP_CR table is a "cross reference" or "link" table that will allow you to create a many to many relationship. This way you can have users in multiple groups without creating extra tables. When a user joins a group, add a row to the USER_GROUP_CR table with the id of the user and the id of the group. You can query this table to find out which groups a user belongs to, or to find out which users are in a group.
You should not create a new table for every group.