Question

我需要一些帮助才能将这组查询转换为单个查询，有人可以帮助我吗？

$occurrences = mysqli_query($link,"SELECT * FROM occurrences WHERE close_id_user order by close_date desc limit 10");
while ($row = mysqli_fetch_assoc($occurrences)){
    $computers = mysqli_query($link,"SELECT * FROM computers id='".$row['id_computer']."'");
    $row_computers = mysqli_fetch_assoc($computers);
    $manufacturers = mysqli_query($link,"SELECT * FROM manufacturers WHERE id='".$row_computers['id_manufacturer']."'");
    $row_manufacturers = mysqli_fetch_assoc($manufacturers);
    $clients = mysqli_query($link,"SELECT * FROM clients WHERE id='".$row_computers['id_client']."'");
    $row_clients = mysqli_fetch_assoc($clients);
}

Answer 1

很难确定在你的问题中结合4的最佳查询是什么。困难在于您不包括如何组合它们。我们可以看到每个表之间的关系基于computer_id，client_id和manufacturer_id，但是很难分辨出while循环的影响以及它如何转换为Join。

同样，以下内容应该让你接近：

SELECT *
FROM occurences
    LEFT OUTER JOIN computers ON occurences.id_computer = computers.id
    LEFT OUTER JOIN manufacturers ON occurences.id_manufacturers = manufacturers.id
    LEFT OUTER JOIN clients ON occurences.id_client = clients.id
WHERE close_id_user

这里我们使用LEFT OUTER JOIN来引入每个表。这可以确保您将获得occurences的所有记录，无论其他三个表中的任何一个是否与其各自的id字段具有匹配值。

查看系统中的结果，然后从那里调整查询，将结果集转换为适合您的格式。

将查询转入subquerys请？

1 个答案: