<code>array (size=2) 'id' => int 139 'key' => string '11111' array (size=2) 'id' => int 139 'key' => string '22222' array (size=2) 'id' => int 159 'key' => string '33333' array (size=2) 'id' => int 159 'key' => string '44444' </code>
合并为
<code>array (size=2) 'id' => int 139 'key' => string '11111,22222' array (size=2) 'id' => int 159 'key' => string '33333,44444' </code>
<code>array (size=2) 'id' => int 139 'key' => string '11111' array (size=2) 'id' => int 139 'key' => string '22222' array (size=2) 'id' => int 159 'key' => string '33333' array (size=2) 'id' => int 159 'key' => string '44444' </code>
合并为
<code>array (size=2) 'id' => int 139 'key' => string '11111,22222' array (size=2) 'id' => int 159 'key' => string '33333,44444' </code>
<code>$arr = [ ["id"=>139, "key"=>"111"], ["id"=>139, "key"=>"222"], ["id"=>159, "key"=>"333"], ["id"=>159, "key"=>"444"] ]; $res = []; foreach( $arr as $item ) $res[ $item['id'] ][] = $item['key']; </code>