在类中加载数据库表

Question

Is it a good practice to load an entire table from a database into a class?

for example a user class? Adding all the information of users in a class?

Answer 1

If your table has a few data it will be fine to get all the information. e.g. if user table has only 3 users; student, tutor and admin along with their ids it is ok to get all the data.

But if the table has a large amount of data it is not a good practice to load whole table. Therefore you can use the operations such as LIMIT to query limited number of rows.

LIMIT example:

SELECT * FROM `my_table` LIMIT 0, 5 

(This will display the first 5 results from 'my_table'.)

For pagination following will be useful:

1. totalRows = the total number of rows in DB. (can be taken using COUNT in sql)
2. itemsPerPage = define how many items you want to show in a single page
3. numberOfPages = totalRows/ itemsPerPage (numberOfPages is useful to display the page numbers in the page).
4. startingItem = (pageNumber - 1) * itemsPerPage
5. SELECT * FROM my_table LIMIT startingItem, itemsPerPage

So basically you will need to pass the pageNumber to a function (when user clicks on a page) in order to retrieve limited number of rows.