如何将查询结果中GROUP_CONCAT返回的逗号分隔member_id字段转为数组

你只需要在返回查询结果前，遍历每一条数据，用explode方法把逗号分隔的member_id字符串拆分为数组即可，修改后的代码如下：

function my_data()
{
    $this->db->select('project.*,GROUP_CONCAT(member_id) AS member_id');
    $this->db->from('project');
    $this->db->group_by("project.project_id");
    $this->db->join('project_meta', 'project.project_id = project_meta.project_id', 'left');
    $query = $this->db->get();
    $result = $query->result_array();

    foreach ($result as $index => $project) {
        // 处理空值场景，避免拆分报错
        if (empty($project['member_id'])) {
            $result[$index]['member_id'] = [];
            continue;
        }
        $memberIdArr = explode(',', $project['member_id']);
        // 如果你需要数组下标从1开始和示例格式完全匹配，保留下面两行即可
        array_unshift($memberIdArr, '');
        unset($memberIdArr[0]);
        $result[$index]['member_id'] = $memberIdArr;
    }

    return $result;
}

内容的提问来源于stack exchange，提问作者gading rengga