Question

I use one table for categories and content.

Value of Categories in pid field is 0.

For example:

Example Table

--------------------------
id | pid | name
--------------------------
1  | 0   | Some catgory 1
--------------------------
2  | 1   | Some content of first category
--------------------------
3  | 1   | Other content of first cat
--------------------------
4  | 0   | Second category
--------------------------
5  | 0   | Category number 3
--------------------------
6  | 5   | Content of category 3
--------------------------
7  | 4   | Content of 2 cat
--------------------------
8  | 5   | Content of 3 cat
--------------------------
9  | 5   | Other Content of 3 cat
--------------------------
10 | 5   | One more content of 3 cat
--------------------------
11 | 4   | Content of 2 cat
--------------------------
12 | 5   | One more content of 3 cat
--------------------------
13 | 1   | First cat content
--------------------------
14 | 1   | Other content of 1 cat

How to get all categories and 10 content items in one query?

Answer 1

To get the results of two separate queries in a single query use UNION ALL:

SELECT id, pid, name
FROM yourtable
WHERE pid = 0
UNION ALL
(
    SELECT id, pid, name
    FROM yourtable
    WHERE pid <> 0
    LIMIT 10
)