[英]MySQL Query - Join Subquery
我有的
我有多個這樣的表:
- tbl_hw_inventar(hw_id,主機名,hw_typ_idfs,hw_created_user_idfs等)
- tbl_hw_typ(hw_typ_id,hw_typ_title等)
- tbl_user(用戶ID,用戶名等)
- tbl_hw_edited(hw_edited_id,hw_edited_client_idfs,hw_edited_date,hw_edited_user_idfs)
我需要的
我要輸出包含以下信息的表:
hw_id | Hostname | created | last edited
12315 | client-01 | 2015-05-06 15:31:06 (username) | 2015-07-02 09:46:17 (username) |
問題
如您所見,我可以獲得帶有外鍵和對“ tbl_hw_typ
”的內部 tbl_hw_typ
之類的信息。 對於帶有“ hw_created_user_idfs
”和內部hw_created_user_idfs
以獲取用戶 ID 用戶名的信息也是如此。
但是,如何獲取最后編輯的 日期時間和用戶名 ?
在我的表“ tbl_hw_edited
”中,我有這樣的條目:
row id | hw_id | datetime | user_id
編碼
到目前為止,我的SQL查詢如下所示:
SELECT `tbl_hw_inventar`.*, `tbl_hw_typ`.`hw_typ_title`, `tbl_user`.`username`, `tbl_hw_edited`.`hw_edited_id`
FROM `tbl_hw_inventar`
INNER JOIN `tbl_hw_typ`
ON `tbl_hw_inventar`.`hw_typ_idfs` = `tbl_hw_typ`.`hw_typ_id`
INNER JOIN `tbl_user`
on `tbl_hw_inventar`.`hw_create_user_idfs` = `tbl_user`.`id`
JOIN (
SELECT MAX(`tbl_hw_edited`.`hw_edited_id`), `tbl_hw_edited`.`hw_edited_client_idfs`
FROM `tbl_hw_edited`
) `tbl_hw_edited` ON `tbl_hw_inventar`.`hw_id` = `tbl_hw_edited`.`hw_edited_client_idfs`
ORDER BY `tbl_hw_inventar`.`hw_id` ASC
那么如何導出信息? 看來我必須在查詢中進行子查詢。 但是我每次嘗試都失敗了。
謝謝你的幫助
編輯
按照提議,我將為每個表提供更多信息(表數據):
-tbl_hw_inventar-
| hw_id | hw_hostname | hw_create_date | hw_create_user_idfs |
| 1 | client-01 | 2015-03-06 11:57:42 | 1 |
| 2 | client-02 | 2015-09-21 21:17:00 | 3 |
-tbl_hw_edited-
| hw_edited_id | hw_edited_client_idfs | hw_edited_date | hw_edited_user_idfs |
| 1 | 1 | 2015-09-24 17:30:22 | 1 |
| 2 | 2 | 2015-09-24 16:33:22 | 2 |
| 3 | 1 | 2015-09-24 23:30:22 | 2 |
| 4 | 2 | 2015-09-24 20:30:22 | 3 |
-tbl_user-
| id | username |
| 1 | ismaelw |
| 2 | skalb |
| 3 | yrumpel |
因此,作為最終結果,我需要這樣的輸出:
| hw_id | hostname | created | edited |
| 1 | client-01 | 2015-03-06 11:57:42 (ismaelw) | 2015-09-24 23:30:22 (skalb) |
如果我正確地解釋了您的表,則需要為每個hw_edited_client_idfs(與hw_id連接)找到最大(編輯日期)
SELECT
hw_edited_client_idfs
, MAX(hw_edited_date) AS last_edit_dt
FROM tbl_hw_edited
GROUP BY hw_edited_client_idfs
通過該結果,您可以將其重新連接到源表,以發現與最大(編輯日期)關聯的用戶
SELECT
het.*
FROM tbl_hw_edited AS het
INNER JOIN (
SELECT
hw_edited_client_idfs
, MAX(hw_edited_date) AS last_edit_dt
FROM tbl_hw_edited
GROUP BY hw_edited_client_idfs
) AS mx ON het.hw_edited_client_idfs = mx.hw_edited_client_idfs
AND het.hw_edited_date = mx.last_edit_dt
然后,該結果使用如下:
SELECT
i.hw_id
, i.hw_hostname
, uc.username created_by
, he.hw_edited_date last_edit_date
, ue.username last_edit_by
FROM tbl_hw_inventar AS i
INNER JOIN tbl_user AS uc ON i.hw_create_user_idfs = uc.id
LEFT OUTER JOIN (
SELECT
het.*
FROM tbl_hw_edited AS het
INNER JOIN (
SELECT
hw_edited_client_idfs
, MAX(hw_edited_date) AS last_edit_dt
FROM tbl_hw_edited
GROUP BY hw_edited_client_idfs
) AS mx ON het.hw_edited_client_idfs = mx.hw_edited_client_idfs
AND het.hw_edited_date = mx.last_edit_dt
) AS he ON i.hw_id = he.hw_edited_client_idfs
LEFT OUTER JOIN tbl_user AS ue ON he.hw_edited_user_idfs = ue.id
產生以下結果:
| hw_id | hw_hostname | username | hw_edited_date | username |
|-------|-------------|----------|-----------------------------|----------|
| 1 | client-01 | ismaelw | September, 24 2015 23:30:22 | skalb |
| 2 | client-02 | yrumpel | September, 24 2015 20:30:22 | yrumpel |
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