I want to create a database which has a table named warehouse which contains the details of each product. I have another table named users. At present there are 2 users in the users table - ABC and DEF.
My main question is user ABC has it's own warehouse and so for user DEF. How can I use the warehouse table for 2 or more different users ?
One to one
If one user own only one warehouse then you should add user_id column in warehouse table. then reference the user_id from user table via foreign key.
One to many
if multiple user owns an warehouse then you should add warehouse column in user table. then reference the warehouse from warehouse table via foreign key.
Many to Many
if an user owns multiple warehouse and and warehouse has multiple owner then you should add a table like warehouse_users and add keep warehouse and user_id.
Related
How to properly implement mysql table relation such that a user can create multiple business and each of those business can have multiple users. thanks
Basically going to be two (possibly 3 tables):
Business Table:
business_id int (this will be the primary key)
business_name
whatever extra fields that relate to the business
User Table:
user_id whatever type (this will be the primary key)
user_name
whatever extra fields that relate to the business
The relational part you can implement in one of two ways:
add the business id to the user table. So user table will have an additional field business_id and will relate back to one of the rows in the business table. This implies a user can only relate to 1 business.
If you want a user to be able to relate to one or more businesses then you need a separate table:
Business_User Table:
business_id int
user_id (whatever type you picked)
I am designing a database for my app. In which I want to do mapping between multiple tables. Now situation is like There is one user table. User can have generate multiple orders. So I was thinking if I can put json obejct of order_id in a column in order table. Or I can create a user_id column in order table & repeat user_id for same user. So which is a better way of doing it?
PS: What is the standard way of doing it?
You should just have user_id in your order table, then make queries like
select * from orders where user_id = *some_user_id*
A user can place multiple orders which in turn can have multiple line items. Each line item can have n quantity of a specific product. So when product comes in picture, then it becomes many to many relationship between user and product because a user can place order for many products and a product can be ordered by many users. So my suggestion is -
Create a User table with UserID
Create a PurchaseOrder table with OrderID, UserID and LineItemID
Create a LineItem table with OrderID, ProductID and LineItemID
Create a SKU table with ProductID
A user can place multiple orders.
Based on this you should maintain three different tables as given below:
User (user_id,...)
Order (order_id,...)
UserOrder (user_id,order_id,...)
Only the primary keys in the above tables are focused
Storing comma separated list or json object will worsen the design. And this is strongly discouraged.
EDIT:
As #NevilleK suggested, the above design is typically used for many-to-many relationships. For one-to-many relationship you can create a foreign key constraint in orders table where user_id should refer to the user_id in the User table.
But still you can adopt the above design for one-to-many relationship since many-to-many qualifies for one-to-many too.
The best way is to have different table for your
User table - which hosts the user information
Transaction table - which will have order_id against each user_id.
Transaction table will carry all the transaction details with user_id. If you create a JSON object, how will you map the USER to the transaction. So at the time of retrieving the json information you will have to map it to the user table anyway. I suggest you the use the above said method, which will help you maintain and scale your application much easily.
in my project a table in mysql database contains two columns one is "UserId"(Primary Key) and other is "Merchants". For example user_A has merchants a,b,c. Now how can i add or delete a merchant for the user_A ?
You should normalise your data structure a have a separate table for users' merchants with user id and merchant as 2 columns. The 3 merchants in the above example will be 3 records in this table. You can easily delete a merchant from this table using a delete statement.
You probably will need another table for merchant details as well.
I have a users table and at the moment a table for storing the users information. The users have a role of buyer or as seller. where the seller has some additional fields that the buyer doesn't have.
Now im wondering what will be a good approach to use. create a table for the users information where i refer to the users id, or two separated tables. One table for the buyers information referring to the user id and one for the sellers information with the exta fields referring to the user id. Where you fill the table according to the users role.
There will be millions of users inside this table so thats something to keep in mind here.
Any help will be appreciated.
Generally you put all the information both types of users share (and that fits on one records of course) in the User table. Then if you need more information by type create a table for that type. If you only need more information right now for sellers, then create a sellers table. If buyers also have specialized fields, then create a buyers table. If however, you do not at this time have any specialized fields to add for the buyers table, then you may not need one at this time. It can be added later if your data model changes.
If this table (these tables) is going to be in a one-to-one relationship with the User table, then make sure to create the Userid as both the FK (to users)and the PK of the child table to maintain data integrity.
You should use two tables, one for users and the other for associates
users
+id
user_name
...
associates
+id
user_id
assoc_type //buyer or seller
...
Let`s say we have the table users. In this table users there are 2 types of users, admin and user. They are linked to an role table through a role_id column but this doesn't matters so much, we can ignore the role table.
An admin has like 5 additional columns for the details and the User has around 25 additional columns for the details.
One option will be to insert all the details columns in the users table, and make them NULL. When inserting a new admin, all the columns for user details will be NULL and when adding a new user all the columns for the admin details will be NULL.
The second option will be to create 2 more tables like users_details and admin_details there will be related to the user_id, and store all the details inside them. And in the users table i will keep only the login info.
Which one you think is the best and why ?