Mysql 如何对查询中的结果进行分组?
我有一个MySQL查询,可以选择用户名和他们的知识(可能不止一个) 它返回类似这样的内容Mysql 如何对查询中的结果进行分组?,mysql,arrays,sorting,group-by,Mysql,Arrays,Sorting,Group By,我有一个MySQL查询,可以选择用户名和他们的知识(可能不止一个) 它返回类似这样的内容 array(5) { [0]=> array(5) { ["user_id"]=> string(2) "30" ["name"]=> string(6) "foo1" ["knowledge"]=> string(15) "Basic Materials" } [1]=> array(5) { ["u
array(5) {
[0]=>
array(5) {
["user_id"]=>
string(2) "30"
["name"]=>
string(6) "foo1"
["knowledge"]=>
string(15) "Basic Materials"
}
[1]=>
array(5) {
["user_id"]=>
string(2) "33"
["name"]=>
string(6) "foo2"
["knowledge"]=>
string(15) "Basic Materials"
}
[2]=>
array(5) {
["user_id"]=>
string(2) "34"
["name"]=>
string(10) "foo3"
["knowledge"]=>
string(9) "Eating"
}
[3]=>
array(5) {
["user_id"]=>
string(2) "34"
["name"]=>
string(10) "foo3"
["knowledge"]=>
string(9) "Financial"
}
[4]=>
array(5) {
["user_id"]=>
string(2) "34"
["name"]=>
string(10) "foo3"
["knowledge"]=>
string(8) "Services"
}
}
如您所见,在本例中,它确实返回五个条目。但是,其中三个具有重复的ID(和名称)。我正在寻找一种只返回三个这样的条目的方法
array(5) {
[0]=>
array(5) {
["user_id"]=>
string(2) "30"
["name"]=>
string(6) "foo1"
["knowledge"]=>
string(15) "Basic Materials"
}
[1]=>
array(5) {
["user_id"]=>
string(2) "33"
["name"]=>
string(6) "foo2"
["knowledge"]=>
string(15) "Basic Materials"
}
[2]=>
array(5) {
["user_id"]=>
string(2) "34"
["name"]=>
string(10) "foo3"
["knowledge"]=>
string(9) "Eating"
}
[3]=>
array(5) {
["user_id"]=>
string(2) "34"
["name"]=>
string(10) "foo3"
["knowledge"]=>
string(9) "Financial"
}
[4]=>
array(5) {
["user_id"]=>
string(2) "34"
["name"]=>
string(10) "foo3"
["knowledge"]=>
string(8) "Services"
}
}
在查询中可以这样做吗
array(5) {
[0]=>
array(5) {
["user_id"]=>
string(2) "30"
["name"]=>
string(6) "foo1"
["knowledges"]=>
array(1) {
[0] => string(15) "Basic Materials"
}
}
[1]=>
array(5) {
["user_id"]=>
string(2) "33"
["name"]=>
string(6) "foo2"
["knowledges"]=>
array(1) {
[0] => string(15) "Basic Materials"
}
}
[2]=>
array(5) {
["user_id"]=>
string(2) "34"
["name"]=>
string(10) "foo3"
["knowledges"]=>
array(1) {
[0] => string(15) "Eating"
[1] => string(15) "Financial"
[2] => string(15) "Services"
}
}
}
我看到的另一个选择是在服务器端处理结果
以下是查询的外观:
SELECT `profiles`.`user_id`, `users`.`name`, `users`.`surname`, `users`.`country`, `profile_knowledges`.`knowledge`
FROM `profiles`
JOIN `users`
ON (`users`.`id` = `profiles`.`user_id`)
JOIN `profile_knowledges`
ON (`profile_knowledges`.`profile_id` = `profiles`.`id`)
对于这种特殊情况,您可以这样写:
$users = array();
while ($row = /* fetch a single row from result set */) {
if (isset($users[$row['user_id']]) == false) {
$users[$row['user_id']] = array(
'id' => $row['user_id'],
'name' => $row['name'],
'knowledges' => array()
);
}
$users[$row['user_id']]['knowledges'][] = $row['knowledge'];
}
不过,最好使用例如来处理这种情况。谢谢,我就是这么想的。是我想到的。。。如何使用ORM实现这一点?:)