[英]Php, MySql join tables, limit records per category
我有兩個表:
物品
ID Name Model_ID
---------------------------------
1 2010 Audi L1 1
2 2014 BMW X2 2
3 2015 Acura L3 3
4 2016 BMW X5 2
5 2012 BMW X3 2
6 2013 BMW X4 2
7 2015 Acura L1 3
8 2011 Acura L2 3
9 2011 Audi L5 1
10 2012 Audi L6 1
品牌品牌
Model_ID Title
---------------------
1 Audi
2 BMW
3 Acura
和以下查詢:
SELECT
b.name,
i.title,
FROM
items AS i
INNER JOIN brands AS b
ON b.Model_ID = i.Model_ID
WHERE i.status = 1
ORDER BY i.created DESC;
上面產生了工作數組:
Array
(
[0] => stdClass Object
(
[name] => 2010 Audi L1
[title] => Audi
)
[1] => stdClass Object
(
[name] => 2014 MBW X5
[title] => BMW
)
...
)
比我使用自定義函數遍歷數組並最終得到
Array
(
[Acura] => Array
(
[0] => stdClass Object
(
[name] => 2015 Acura L1
[title] => Acura
)
...
)
[BWM] => Array
(
[0] => stdClass Object
(
[name] => 2016 BMW X5
[title] => BWM
)
...
)
[Audi] => Array
(
[0] => stdClass Object
(
[name] => 2010 Audi L1
[title] => Audi
)
...
)
)
現在,我可以使用foreach循環並限制每個品牌顯示x個項目,但是這個想法是在數據庫中完成,因此,除了提取所有記錄,我希望每個品牌可以限制5個項目。
注意:我未列出用於對記錄進行排序的其余表字段,例如創建的。
$ q ='從品牌ORDER BY標題ASC中選擇Model_ID AS ID';
$ r = mysql_query($ q);
$ model_ids = array();
while($ brand = mysql_fetch_assoc($ r)){$ model_ids [] = $ brand ['id']; }
$q = array(); foreach($mode_ids AS $model_id) { $q[] = '(SELECT b.name, i.title FROM items AS i INNER JOIN brands AS b ON b.Model_ID = i.Model_ID WHERE b.Model_ID = '.(int)$model_id.' AND i.status = 1 ORDER BY i.created DESC LIMIT 5)'; } if(!empty($q)) { $q = implode(' UNION ALL ', $q); $r = mysql_query($q); while($record = mysql_fetch_object($r)) { var_dump($record); } }
結果,我們將獲得結果查詢的記錄:
(從項目中選擇“ b.name”,“ i.title”作為“ i i.INNER JOIN”品牌作為“ b ON”。b.Model_ID= i.Model_ID,b.Model_ID = 1並且i.status = 1由i。創建的DESC LIMIT 5)
全聯盟
(從項目中選擇b.name,i.title作為AS i INNER JOIN品牌作為b.b.Model_ID = i.Model_ID WHERE b.Model_ID = 2 AND i.status = 1按i。創建的DESC LIMIT 5排序)
全聯盟
(從項目中選擇“ b.name”,“ i.title”作為“ i i.INNER JOIN”品牌作為“ b ON”。b.Model_ID= i.Model_ID WHERE b.Model_ID = 3並且i.status = 1由i。創建的DESC LIMIT 5)
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