從同一張表中選擇不同的結果

Question

我在帖子表中有以下結構（示例）：

id | id_author | content | date | ft
1  | 1         | hi!     | 2016 | 2
2  | 1         | hello!  | 2016 | 3
3  | 1         | welcome | 2016 | 1
4  | 1         | test!   | 2016 | 2

我有query ：

SELECT id, id_author, content, date, ft FROM post where id_author = '$author' ORDER BY id DESC LIMIT 7

但是，我也需要select與ft LIMIT 4相對應的ft的帖子。 像這樣：

SELECT id, id_author, content, date, ft FROM post where id_author = '$author' and ft = 1 ORDER BY id DESC LIMIT 4

SELECT id, id_author, content, date, ft FROM post where id_author = '$author' and ft = 2 ORDER BY id DESC LIMIT 4

SELECT id, id_author, content, date, ft FROM post where id_author = '$author' and ft = 3 ORDER BY id DESC LIMIT 4

我可以使用foreach來對ft進行“過濾”，例如：

foreach($query as $ex) {
    switch($ex["ft"]) {
        ...
    }
}

但是，我的第一個query需要有LIMIT 7 ，對ft的querys需要從所有帖子中選擇最后4個結果。

如何執行此操作而不必執行多次querys ？

編輯 ：

我需要顯示的最后7個（一般）在一個div ，最后4帖與圖像（ ft = 1在另一個） div ，最后4帖與提及（ ft = 2 ）在另一個div和最后4個帖與在另一個div主題標簽（ ft = 3 ）。

Answer 1

您可以使用UNION運算符執行此操作。

SELECT
    'General' AS post_type,
    id,
    id_author,
    content,
    date,
    ft
FROM
    Post
WHERE
    id_author = '$author'
ORDER BY
    id DESC
LIMIT 7
UNION ALL
SELECT
    'Image' AS post_type,
    id,
    id_author,
    content,
    date,
    ft
FROM
    Post
WHERE
    id_author = '$author' AND
    ft = 1
ORDER BY
    id DESC
LIMIT 4
UNION ALL
SELECT
    'Mentions' AS post_type,
    id,
    id_author,
    content,
    date,
    ft
FROM
    Post
WHERE
    id_author = '$author' AND
    ft = 2
ORDER BY
    id DESC
LIMIT 4
UNION ALL
SELECT
    'Hashtags' AS post_type,
    id,
    id_author,
    content,
    date,
    ft
FROM
    Post
WHERE
    id_author = '$author' AND
    ft = 3
ORDER BY
    id DESC
LIMIT 4