需要帮助建立一个mysql查询，将一个变量与两个表进行比较

Question

我建立了2个查询，将$project_id变量与MEETING_AGENDA所示的2个表MEETING ＆ MEETING_AGENDA进行比较：

                                    +---------------------+
                +------------+      |    MEETING_AGENDA   |
                |  MEETING   |      +---------------------+
                +------------+      | meeting_agenda_id   |
                | meeting_id |----->| meeting_id          |
$project_id --->| project_id |      | meeting_agenda_name |
                +------------+      +---------------------+

该流程图背后的逻辑是，我存储了一个名为$project_id的变量，该变量充当输入。 如果$project_id = MEETING.project_id那么我需要存储MEETING.meeting_id的列表。 MEETING存在project_id的多个重复项，从而产生了一系列meeting_id的（仅作澄清）。 如果有任何的MEETING.meeting_id的= MEETING_AGENDA.meeting_id然后打印meeting_agenda_name 。

我的混乱尝试（有效）如下所示：

$project_id = $_SESSION['PROJECT_ID'];
$query1 = 
"
SELECT meeting_id, meeting_project_id
FROM MEETING
WHERE project_id = $project_id
";

$result1 = mysqli_query($con, $query1) or die("Query error: " . mysqli_error($con));

while($row = mysqli_fetch_array($result1)){
  $meeting_ids = $row['meeting_id'];

  $query2 = 
  "
  SELECT *
  FROM MEEITNG_AGENDA
  WHERE meeting_id = $meeting_ids
  ";

  $result2 = mysqli_query($con, $query2) or die("Query error: " . mysqli_error($con));

  while($row2 = mysqli_fetch_array($result2)){
    echo $row2['meeting_agenda_name'] . "<br>"  
  }
}

我使用2个查询，如果可能的话，我想将其清理为1个查询。 我在单个查询中尝试了各种尝试，但没有任何帮助。 这是我最近的尝试。

新查询：

 $query = 
 "
 SELECT MEETING.project_id, MEETING.meeting_id, MEETING_AGENDA.*
 FROM MEETING
 WHERE MEETING.project_id = $project_id
 INNER JOIN MEETING.project_id
 ON $project_id = MEETING.project_id
 ";

对于缺乏mysql知识，我深表歉意，但对您的任何帮助，我们深表感谢。

Answer 1

您可以通过以下查询在单个查询中获得该信息：

SELECT m.project_id, m.meeting_id, ma.*
FROM MEETING m
INNER JOIN MEETING_AGENDA ma ON ma.meeting_id  = m.meeting_id 
WHERE m.project_id = $project_id