php数组练习之----查询数组中某key的键值相同的个数、数组的格式转换、合并数组_PHP教程

$array  =  array() {

                 [0]=> array(6) {
                ["id"]=> string(1) "2"
                ["lessonid"]=> string(3) "200"
                ["userid"]=> string(4) "6038"
                ["username"]=> string(8) "jsc11101"
                ["lessontitle"]=> string(47) "Module1-Unit2 I'm From China "
                ["courseid"]=> string(1) "4"
                }

                 [1]=> array(6) {
                ["id"]=> string(1) "3"
                ["lessonid"]=> string(3) "201"
                ["userid"]=> string(4) "6038"
                ["username"]=> string(8) "jsc11101"
                ["lessontitle"]=> string(33) "Module2-Unit1 I Can Speak English"
                ["courseid"]=> string(1) "4"
                }
                 [5]=> array(6)
                   。。。。。。。。。。。。。。。。。。。。。。。。
}

相同lessonid的学习次数

$study_num = array();

foreach($array as $value){

                 $study_num[$value['lessonid']]=(empty($study_num[$value['lessonid']])?0:$study_num1[$value['lessonid']])+1; 

                                                                                  //如果$study_num[$value['lessonid']为第一次遍   历赋值为空

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}

学习次数：   $study_num[$lessionid]

转换成以lessonid为key的数组

$lessonid_array = array();

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foreach($array as $key => $value){

                 $lessonid_array[$value[lessonid]]=$value;

}

学习课文名称：  $lessonid_array[$lessonid]['lessontitle']

合并数组

foreach($study_num as $key=>$value){

                 $lessonid_array[$key][count]=$value;

}

 输出数组形式如下
               

$a_array  = array(){              
          lessonid号 => array(7) {
                  

                 ["id"]=> string(1) "3"
                ["lessonid"]=> string(3) "学习课文ID"
                ["userid"]=> string(4) "6038"
                ["username"]=> string(8) "jsc11101"
                ["lessontitle"]=> string(33) "学习课文名称"
                ["courseid"]=> string(1) "4"
                ["count"]=>"学习次数"

}
}