I want to create a table structure of the following requirement :
I have some main categories(e.g Electronics, Dress etc.). I want to add subcategories under these categories upto three level.
Suppose main category is Electronics. It's child category is computer. Computer's child category is Laptop and Laptop's child category is Dell.
( Electronics => computer => Laptop => Dell )
Like the above example there are many categories and sub categories.
So, what is the appropriate table structure of it?
I will suggest to create one table with column parent_id.
For example:
TABLE category
category_id,
category_name
category_parent_id
parent_id will contain the id of parent_id.
For ex.
category_id | category_name | category_parent_id
1 | Electronics | 0
2 | Dress | 0
3 | Computer | 1
4 | T-shirt | 2
5 | Llaptop | 3
6 | Dell | 5
Related
How to create multilevel Category tree from same table in Laravel. I may have 2 level categories or may be up to 5th level Subcategories and I want this dynamic in Laravel.
For example-
Category 1
|_ Subcat 1-1
|_ Subcat 1-2
Category 2
|_Subcat 2-1
| |_Subcat 2-1-1
| | |_ Subcat 2-1-1-1
| | |_ Subcat 2-1-1-2
| |
| |_Subcat 2-1-2
|
|_Subcat 2-2
Category 3
You can introduce parent_id column in your table
For items at the first level , the the id and parent_id is simillar
CategoriesTable { id ,name,parent_id }
Here is how the data is stored in the table
id , name , parent_id
1 , Books , 1
2 , Clothes ,2
3 , counterbook,1
4 , jeans , 2
5 , cars,5
The chain can go on and on , so in your foreach loop you have put an if id = parent_id then you know to determine 1st level
I will have a table that is full of information that involves other tables (relations). Most of the information in this table will only have the ID's of the referencing related table. If I were to use "products" as an example for this table it may look like this for some of the columns:
id | name | type_id | price_id | location_id | sale_id
----------------------------------------------------------------
1 | prod1 | 1 | 1 | 2 | 4
2 | prod2 | 2 | 1 | 1 | 1
3 | prod3 | 3 | 2 | 6 | 2
4 | prod4 | 1 | 2 | 3 | 4
I'm trying to take this "products" table and dump it out into a list. I would need to look up all of the items in these columns as I dump it out (the relation). I know how to do belongsToMany and hasMany, but I'm not sure how I can do this in one shot with an Eloquent model if I have a "products" model? Should I just make the products table just a pivot table? Can I do it with an Eloquent model or should I use query builder directly? I think if I were to use withPivot it would return the extra columns but the raw ID value from the column. I would need the value lookup from their respective table (the relation).
Tried something like this:
public function productItems(){
return $this->belongsToMany(Product::class)->withPivot(["type_id","price_id",...]);
}
As suggested by #BagusTesa, you should eager load your relations:
$products = Product::with(['type', 'price', 'location'])->get();
That will query for the related models allowing you to access them as model properties:
foreach ($products as $product){
// $product->type;
// $product->price;
// $product->location;
}
I have a table Which is as below:
quotes_glass_types
id | name | parent_id
1 | Annealed glass | Null
2 | Clear Float Glasss | 1
3 | Tinted glass | 1
4 | Toughened glass | Null
5 | Clear toughened Glass | 4
Here, name having Null parent_id are the parent.
How do i display glass name along with their parent in laravel? for example;
{
id:2,
name:Clear Float glass,
category:Annealed glass
}
what do i do after this?:
$glass=\DB::table('quotes_glass_types')->select('id','name','parent_id as category')->get();
If you want to get Name with Parent Name than you can use below query :
SELECT qgt.name,pqgt.name FROM quotes_glass_types as qgt LEFT JOIN quotes_glass_types as pqgt ON qgt.id = pqgt.parent_id
You have to use LEFT JOIN on the same table. I don't know how to write this query in Laravel but this query works in phpmyadmin.
Please check it.
You can do like this-
DB::table('quotes_glass_types')
->select('quotes_glass_types.*', 'qgt.name as parent_name')
->leftjoin('quotes_glass_types as qgt', 'qgt.id', '=', 'quotes_glass_types.parent_id')
->get();
I have the following table called questions in HQL Hibernate:
ID | Name
1 | Bread
2 | Bread
3 | Rise
4 | Rise
I want to select each PRODUT only once and if there are multiple PRODUCT with the same name, select the one of the highest id. So, the expected results:
ID | NAME
3 | Bread
4 | Rise
I use the following query:
from Product AS E group by E.producto
So it selects the first 'Product' it encounters instead of the last one.
Thanks
The syntax is almost identical to SQL:
select max(p.id), p.name from Product p group by p.name
Relevant documentation:
http://docs.jboss.org/hibernate/core/4.3/manual/en-US/html/ch16.html#queryhql-aggregation
http://docs.jboss.org/hibernate/core/4.3/manual/en-US/html/ch16.html#queryhql-grouping
I am using the following LINQ query for my profile page:
var userData = from u in db.Users
.Include("UserSkills.Skill")
.Include("UserIdeas.IdeaThings")
.Include("UserInterests.Interest")
.Include("UserMessengers.Messenger")
.Include("UserFriends.User.UserSkills.Skill")
.Include("UserFriends1.User1.UserSkills.Skill")
.Include("UserFriends.User.UserIdeas")
.Include("UserFriends1.User1.UserIdeas")
where u.UserId == userId
select u;
It has a long object graph and uses many Includes. It is running perfect right now, but when the site has many users, will it impact performance much?
Should I do it in some other way?
A query with includes returns a single result set and the number of includes affect how big data set is transfered from the database server to the web server. Example:
Suppose we have an entity Customer (Id, Name, Address) and an entity Order (Id, CustomerId, Date). Now we want to query a customer with her orders:
var customer = context.Customers
.Include("Orders")
.SingleOrDefault(c => c.Id == 1);
The resulting data set will have the following structure:
Id | Name | Address | OrderId | CustomerId | Date
---------------------------------------------------
1 | A | XYZ | 1 | 1 | 1.1.
1 | A | XYZ | 2 | 1 | 2.1.
It means that Cutomers data are repeated for each Order. Now lets extend the example with another entities - 'OrderLine (Id, OrderId, ProductId, Quantity)andProduct (Id, Name)`. Now we want to query a customer with her orders, order lines and products:
var customer = context.Customers
.Include("Orders.OrderLines.Product")
.SingleOrDefault(c => c.Id == 1);
The resulting data set will have the following structure:
Id | Name | Address | OrderId | CustomerId | Date | OrderLineId | LOrderId | LProductId | Quantity | ProductId | ProductName
------------------------------------------------------------------------------------------------------------------------------
1 | A | XYZ | 1 | 1 | 1.1. | 1 | 1 | 1 | 5 | 1 | AA
1 | A | XYZ | 1 | 1 | 1.1. | 2 | 1 | 2 | 2 | 2 | BB
1 | A | XYZ | 2 | 1 | 2.1. | 3 | 2 | 1 | 4 | 1 | AA
1 | A | XYZ | 2 | 1 | 2.1. | 4 | 2 | 3 | 6 | 3 | CC
As you can see data become quite a lot duplicated. Generaly each include to a reference navigation propery (Product in the example) will add new columns and each include to a collection navigation property (Orders and OrderLines in the example) will add new columns and duplicate already created rows for each row in the included collection.
It means that your example can easily have hundreds of columns and thousands of rows which is a lot of data to transfer. The correct approach is creating performance tests and if the result will not satisfy your expectations, you can modify your query and load navigation properties separately by their own queries or by LoadProperty method.
Example of separate queries:
var customer = context.Customers
.Include("Orders")
.SingleOrDefault(c => c.Id == 1);
var orderLines = context.OrderLines
.Include("Product")
.Where(l => l.Order.Customer.Id == 1)
.ToList();
Example of LoadProperty:
var customer = context.Customers
.SingleOrDefault(c => c.Id == 1);
context.LoadProperty(customer, c => c.Orders);
Also you should always load only data you really need.
Edit: I just created proposal on Data UserVoice to support additional eager loading strategy where eager loaded data would be passed in additional result set (created by separate query within the same database roundtrip). If you find this improvement interesting don't forget to vote for the proposal.
(You can improve performance of many includes by creating 2 or more small data request from data base like below.
According to my experience,Only can give maximum 2 includes per query like below.More than that will give really bad performance.
var userData = from u in db.Users
.Include("UserSkills.Skill")
.Include("UserIdeas.IdeaThings")
.FirstOrDefault();
userData = from u in db.Users
.Include("UserFriends.User.UserSkills.Skill")
.Include("UserFriends1.User1.UserSkills.Skill")
.FirstOrDefault();
Above will bring small data set from database by using more travels to the database.
Yes it will. Avoid using Include if it expands multiple detail rows on a master table row.
I believe EF converts the query into one large join instead of several queries. Therefore, you'll end up duplicating your master table data over every row of the details table.
For example: Master -> Details. Say, master has 100 rows, Details has 5000 rows (50 for each master).
If you lazy-load the details, you return 100 rows (size: master) + 5000 rows (size: details).
If you use .Include("Details"), you return 5000 rows (size: master + details). Essentially, the master portion is duplicated over 50 times.
It multiplies upwards if you include multiple tables.
Check the SQL generated by EF.
I would recommend you to perform load tests and measure the performance of the site under stress. If you are performing complex queries on each request you may consider caching some results.
The result of include may change: it depend by the entity that call the include method.
Like the example proposed from Ladislav Mrnka, suppose that we have an entity
Customer (Id, Name, Address)
that map to this table:
Id | Name | Address
-----------------------
C1 | Paul | XYZ
and an entity Order (Id, CustomerId, Total)
that map to this table:
Id | CustomerId | Total
-----------------------
O1 | C1 | 10.00
O2 | C1 | 13.00
The relation is one Customer to many Orders
Esample 1: Customer => Orders
var customer = context.Customers
.Include("Orders")
.SingleOrDefault(c => c.Id == "C1");
Linq will be translated in a very complex sql query.
In this case the query will produce two record and the informations about the customer will be replicated.
Customer.Id | Customer.Name | Order.Id | Order.Total
-----------------------------------------------------------
C1 | Paul | O1 | 10.00
C1 | Paul | O2 | 13.00
Esample 2: Order => Customer
var order = context.Orders
.Include("Customers")
.SingleOrDefault(c => c.Id == "O1");
Linq will be translated in a simple sql Join.
In this case the query will produce only one record with no duplication of informations:
Order.Id | Order.Total | Customer.Id | Customer.Name
-----------------------------------------------------------
O1 | 10.00 | C1 | Paul