Question

我正在尝试从两个不同的表中查询两个不同的列，我可以在其中计算某些列的数量。我可以在两个单独的查询中执行此操作，但我认为这会在将来导致速度降低。我想要的是一个查询，我只能在一个查询中显示这两个计数。

我尝试使用两个分开的选择语句，但是我认为这不好，我也尝试使用Union All，但是结果不是我期望的。

    upload_monitoring (12 Columns)
    upm_FileName    | upm_Status
    ----------------+--------------
    Monitoring_0608 | Distributed
    Monitoring_0607 | Distributed
    Monitoring_0606 | Distributed
    Monitoring_0605 | Uploaded
    (100 rows)

    distribute_monitoring (7 Columns)
    dist_ProductName   | dist_Status
    -------------------+--------------
    Monitoring_0608    | Pending
    Monitoring_0607    | Pending
    Monitoring_0606    | Pending
    Monitoring_0605    | Touched
    (100 rows)

我尝试了这些：

$query2 = "
    SELECT
        COUNT(upm_Status) AS total_DistItems
    FROM
        upload_monitoring
    WHERE
        upm_Status = 'Distributed'                                   
    AND
        upm_FileName = '$upm_FileName'
    ";

$result2 = mysqli_query($connection, $query2);
$fetchResult2 = mysqli_fetch_assoc($result2);
$total_DistItems = $fetchResult2['total_DistItems'];

$query3 = "
    SELECT
        COUNT(dist_Status) AS total_PendItems
    FROM
        distribute_monitoring
    WHERE
        dist_Status = 'Pending'
    AND
        dist_Product = '$upm_FileName'
    ";

$result3 = mysqli_query($connection, $query3);
$fetchResult3 = mysqli_fetch_assoc($result3);
$total_PendItems = $fetchResult3['total_PendItems'];

我也尝试过这些

$query2 = "                                              
    SELECT
        upm_Status,
        COUNT(upm_Status) AS total_DistItems
    FROM
        upload_monitoring
    WHERE
        upm_Status = 'Distributed' 
    AND
        upm_FileName = '$upm_FileName'
    UNION ALL
    SELECT
        dist_Status,
    COUNT(dist_Status) AS total_PendItems
    FROM
        distribute_monitoring
    WHERE
        dist_Status = 'Pending'
    AND
        dist_Product = '$upm_FileName'
    ";

$result2 = mysqli_query($connection, $query2);

无论结果如何

    upm_Status  | total_DistItems
    ------------+--------------
    Distributed | 34
    Pending     | 12

我希望结果像这样。

    upm_Status  | total_DistItems | dist_Status | total_PendItems
    ------------+-----------------+-------------+-----------------
    Distributed | 34              | Pending     | 12

Answer 1

这是一种方法：

SELECT u.*, d.*
FROM (SELECT 'Distributed' as upm_Status,
             COUNT(*) AS total_DistItems
      FROM upload_monitoring
      WHERE upm_Status = 'Distributed' AND
            upm_FileName = ?
     ) u CROSS JOIN
    (SELECT 'Pending' as dist_Status, COUNT(dist_Status) AS total_PendItems
     FROM distribute_monitoring
     WHERE dist_Status = 'Pending' AND
           dist_Product = ?
     ) d;

请注意，我将$upm_filename替换为?。这表明您应该使用参数将值传递到查询中，而不是使用此类值来修饰查询字符串。您的方法会使您面临意外语法错误和SQL注入攻击的风险。

如何计算来自两个不同表的两个单独的列？

1 个答案: