<?php  
    function assoc_unique($arr, $key) {   
        $tmp_arr = array();   
        foreach($arr as $k => $v) {   
            if(in_array($v[$key], $tmp_arr)) {   
                unset($arr[$k]);   
            } else {   
                $tmp_arr[] = $v[$key];   
            }   
        }   
        sort($arr);   
        return $arr;   
    }   

    $aa = array(   
        array('id' => 123, 'name' => '张三'),   
        array('id' => 123, 'name' => '李四'),   
        array('id' => 124, 'name' => '王五'),   
        array('id' => 125, 'name' => '赵六'),   
        array('id' => 126, 'name' => '赵六')   
    );   
    $key = 'name';   
    assoc_unique(&$aa, $key);   
    print_r($aa);  
?>