php - 基于计数的限制

Question

我对类别和内容使用一个表格。

pid 字段中 Categories 的值为 0。

例如:

示例表

--------------------------
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

如何在一次查询中获取所有类别和 10 个内容项？

Answer 1

要在单个查询中获取两个单独查询的结果，请使用 UNION ALL:

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