I'm developing website in which will be categorized advertisements. In each category will be possible different fields of input (example: for car there will be motor size, for cat there will be a race). So I'm thinking how to build database to manage this (I will use MYSQL database). One way you can see in attached picture, I know that also is solution to create table for each values datatape, but I'm wondering that it will slow down a website. This solution which is in picture will generate empty fields in sp_advertisement_value table what isn't good also.
What is in your opinion the best solution? Maybe there is something else?
p.s. Here is a link to database market.
You can store it like name/value pairs (more or less same to what you is described in the image you attached).
A simple schema would be a table having two columns name and value. Instead of having a column for each data type like value_int, value_string etc. have one single column value who's data type can be varchar (or Text as seems fit to you). You can do all the data conversion in your application code as per your needs.
You can do some normalization here too for instance instead of saving name you can make a separate lookup table named parameters having id, name and other related information and have the parameter_id in the table where you are storing parameter values.
Related
I wanted to use a relational database(MySql) to store my data as key-value pair.
I would be getting no. of key-value pairs dynamically.
I can create a simple table to store them in separate columns.
Values can be of type- int, varchar, text or date.
The problem which I am facing is:
When I need to run a query on key whose value should be an integer and I need to use and greater than or less than query with it. Same case when I need to use between query with date fields.
How can I achieve it?
------------------------------------------------Edit---------------------------------------------------
For greater clarity, I am providing the background for this question which I have divided into three parts:
1. Data 2: Use Case 3. Possible Designs
1. Data
Suppose I'm creating data store for census of a country**(Just an example)**. Fields for storing data would be different for male, female, boy or girl and also it will vary according to the person's profession. The number of fields depends on the requirement which can increase up to 500 or more.
2. Use Case
Show a paginated list of persons whose monthly income is between $7000 to $10000. User can click on any page number and the database should directly fetch the data for that page number. For example, if we are showing 10 results in a page and user clicks on the 5th page then we should show him the list of the person's from 40 to 50.
Some of the values belonging to a particular group store description which can have large data. So they should be stored as TEXT.
3. Possible Designs
I can create a separate table for each different type and store their data in respective fields. But the problem I'm thinking about this approach is that MySQL table has a maximum row size limit of 65,535 bytes. Going by this approach and storing all data horizontally might cross the max size limit. As the number of fields are not fixed and can change as per requirement.
Instead of storing data horizontally I can store them vertically using Entity Attribute Value design(key-value pair). For now, the increase in the number of rows due to this design is not a problem. Using this I can store data of all male, female or child in the same table. But the problem with this approach is:
I will lose the Datatype of certain important fields. I can not query and get the list of persons whose income is more than 1000.
For storing data or all fields in single Value type, I need to make it varchar. But some fields store large data which requires TEXT as the type.
Considering the above problem, I thought that instead of creating only one value field, I will create multiple value fields like value_int, value_varchar, value_date or value_text.
DB structure
For this problem, I will be using MySQL and cannot change the DB due to certain restrictions. So I am looking for a design with MySQL only.
Going by key-value approach is a good idea or not? Or any other possible design which can be used?
In very general terms, if you know the entities and attributes of your problem domain, and the data is relational, I'd use a relational schema (your "possible design 1"). If you actually encounter problems with maximum row width, your problem domain might contain logical subgroupings of attributes, so you can split them into separate table.
For instance:
Person (id, name, ...)
Person_demographics (person_id, age, location, ...)
Person_finance (person_id, income, wealth...)
If you don't know the entities and attributes in advance, I recommend using MySQL's JSON support. or XML support. This gives you access to much better query options than EAV.
The problem with EAV-like solutions in your scenario is that any non-trivial queries end up being incredibly complicated - "find all responses where salary is between x and y, and the age is z, in locations (a, b, c)" turns into a horrible mess of SQL, but with XPath this is pretty straightforward.
I have table and in the images column I am saving the names of the images needed for that row data, I want to know if there is any way to read multiple image name which are in the same column(and row) and fetch corresponding image from the folder.
I can read one image name and fetch that image from the folder, but not more than one.
Do I have to create multiple column to achieve this?
Even of you could, its not a good design to store multiple image names on the same column(not just for images, but any type of data in general), research about "normal forms"(or normalization) in database design, the best approach would be to store them on another table with a 1 to many relationship(the images table would have a foreign key to the original row),this way you can easily fetch image by image with a simple join ,and use the current code "for one image" you already have
Microsoft SQL 2016 have JSON storage support. You could store the names in JSON in a single column and return the result as JSON. Something like:
SELECT a.ImageNames FROM table1 a FOR JSON
Then you could load the JSON into an object with a list property.
Some variation of that. It's difficult to tell because we don't know what language or framework you're using other than MS SQL. But if you want to store multiple values in a single column/row, JSON would be a good way to do it.
You could also just use a simple CSV value.
I’m using a heavy duty CMS and have created a new data field for a certain content type. the data field is named ‘sort order’ or possibly ‘sort_order’. I’m assuming the data field is added to a table and have no way of knowing which table it was added to. When viewing the database via phpmyadmin there are simply too many tables to go looking for it.
Is there any way possible to do a search to find which table would contain this column name? or maybe an alternate method would be some look for most recent updated table?
I'm trying to do it like this:
Every single user can choose fields (like structures on MySQL) where this fields can handle their respective value, it's like doing a DB inside a DB.
But how can I do it using a single table?
(not talking about user accounts etc where I should be able to use a pointer to his own "structure")
Do something like: varchar Key where register something like "Name:asd" where PHP explode : to get the respective structure ('name' in this case) and the respective value? ('asd')
Use BLOB? can someone turn the light on for me? I don't know how to do something where works better than my current explanation...
I know my text is confuse and sorry for any bad english.
EDIT:
Also, they could add multiple keys/"structures" where accepts a new value
And they are not able to see the Database or Tables, they still normal users
My server does not support Postogre
In my opinion you should create two tables.
with the user info
with 3 fields (userid, key and value)
Each user has 1 record in the first table. Each user can have 0 or more records in the second table. This will ensure you can still search the data and that users can easily add more key/value pairs when needed.
Don't start building a database in a database. In this case, since the user makes the field by himself there is no relation between the fields as I understand? In that case it would make sense to take a look at the NoSQL databases since they seem to fit very good for this kind of situations.
Another thing to check is something like:
http://www.postgresql.org/docs/8.4/static/hstore.html
Do not try to build tables like: records, fields, field types etc. That's a bad practice and should not be needed.
For a more specific answer on your wishes we need a bit more info about the data the user is storing.
While i think the rational answer to this question is the one given by PeeHaa, if you really want the data to fit into one table you could try saving a serialized PHP array in one of the fields. Check out serialize and unserialize
Generates a storable representation of a value
This is useful for storing or passing PHP values around without losing
their type and structure.
This method is discouraged as it is not at all scalable.
Use a table with key-value pairs. So three columns:
user id
key ("name")
value ("asd")
Add an index on user id, so that you can query a user's attributes easily. If you wanted to query all users with the same properties, then you could add a second index on key and/or value.
Hope you are using a programming language also to get the data and present them.
You can have a single table which has a varchar field. Then you store the serialized data of the field structure and their value in that field. When you want to get the structure, query the data and De-serialize that varchar field data.
As per my knowledge every programming language supports serialization and De-serialization.
Edited : This is not a scalable option.
I have created the following database layout, and started coding the application. The more I read, the more I realize my database layout is probably incorrect / inefficient / a bad idea. Before I develop too much code using this layout, I want to make sure I am doing it "correctly".
Basically I have a list of ~2000 stores, and a list of ~50 promotional codes. I need to store whether or not each code is valid at each store. Right now I chose to store each store number as a column header, with the first column containing all of the different possible codes. Here's an image of part of the table so far (1 represents the code being valid, 0 invalid at that store).
The promotional codes will change relatively frequently, but the store numbers should be relatively static, and not change very much.
This is my first time creating a database from scratch like this, and I am a beginner at using mysql, so any help is much appreciated!
You should better use a table for your stores. If you don't, when one store will be added you'll spend a lot of time to add a new field...
Here is what I would do:
table store will contains your 2000s stores
id
name
table code will contains your 50 codes
id
name
table code_store will contains only the valid codes ID, and related store_id(no need to save invalid ones I guess)
code_id
store_id
This type of relation is called many-to-many. I typically have three table for this type of situation. One table for the stores, one for the promo codes, and a third relational table that would have two columns: the store id and the promo id.