Question

I have a MySQL table with 3 columns *ID, Item_ID, Dependency*

I want to know the best way to recursively check through the dependencies for example say i am checking for Item_ID 3’s dependencies and it requires Item_ID 2 i would then need to check the dependencies for Item_ID 2

What is the best way to achieve this with PHP?

ID | Item_ID | Dependency |
---+---------+------------+
1  | 3       | 2          |
---+---------+------------+
2  | 2       | 4          |
---+---------+------------+
3  | 2       | 5          |
---+---------+------------+

Answer 1

pseudo code:

func myQuery(item_ID) {
    query (item_ID)
    if (!item_ID.dependency())

    else (myQuery(item_ID.dependency())
}

This will continue down the column until you reach an item that does not have a dependency.

Summary of process: Pass the first item to the function. Check if it has a dependency, if it does, call the function again with that dependency. Otherwise do nothing and the function will return. of course you’ll want to save the items returned by the query but I’ll leave that to you. You would probably want that statement at the very end of the function so when all is said and done you have your data ordered from no dependencies to most dependencies.