Question

请查看以下代码以获取更多信息。

 // Finding a list of schools.
    $schoolQuery = "SELECT DISTINCT stud_school AS schools FROM students";
    $schoolsList = mysqli_query($conn, $schoolQuery);
    while ($row = mysqli_fetch_assoc($schoolsList)) {
    echo $row['schools'];
    }
    echo "<br>";

上面的代码应该在我的数据库表中的列中收集唯一值。

这是输出：

ArkCCAPM（Ark，CCA和PM是学校的首字母）。

$allSchools = mysqli_real_escape_string($row['schools']);
// Sums upp all the points recieved by each student for specific school
$myQuery = "SELECT SUM(result_studpoints) AS total FROM result WHERE stud_id IN (SELECT stud_id FROM students WHERE stud_school = 'CCA')";
$result = mysqli_query($conn, $myQuery);
$data = mysqli_fetch_assoc($result);

echo "Total CCA: ".$data['total'];

以上代码仅计算学校CCA的总积分。我想要做的是使用唯一值（列出我数据库中的所有学校）并将其实现到上面的计算代码中，这样它不仅可以计算CCA的总数，还可以计算出唯一值中列出的所有学校的总数。所以输出看起来像这样：

Total CCA: 16
Total PM: 17
Total Ark: 9

提前致谢。

Answer 1

$allSchools = mysqli_real_escape_string($row['schools']);
// Sums upp all the points recieved by each student for specific school
$myQuery = "SELECT students.stud_school, SUM(result_studpoints) AS total FROM result JOIN students ON students.stud_id = result.stud_id GROUP BY students.stud_school";
$result = mysqli_query($conn, $myQuery);
$data = mysqli_fetch_assoc($result);

echo "Total " . $data['stud_school'] . ": ".$data['total'] . "<br />";

Answer 2

试试这个：

// Finding a list of schools.
$schoolQuery = "SELECT DISTINCT stud_school AS schools FROM students";
$schoolsList = mysqli_query($conn, $schoolQuery);
while ($row = mysqli_fetch_assoc($schoolsList)) 
{
    $allSchools = mysqli_real_escape_string($conn, $row['schools']);
    // Sums upp all the points recieved by each student for specific school
    $myQuery = "SELECT SUM(result_studpoints) AS total FROM result WHERE stud_id IN (SELECT stud_id FROM students WHERE stud_school = '$allSchools')";
    $result = mysqli_query($conn, $myQuery);
    $data = mysqli_fetch_assoc($result);

    echo "Schools: ".$row['schools']." --> Total CCA: ".$data['total'];
    echo "<br>";

}

Answer 3

您可以直接使用此唯一查询，而不是首先查询学校列表，然后使用返回的结果通过其他查询获得最终结果：

$myQuery = "
  SELECT SUM(result_studpoints) AS total, school
  FROM result
  JOIN students ON result.stud_id = students.stud_id
  GROUP BY school
";

然后按照您的计划使用其结果。

SQLfiddle

注意：正如一些评论已经指出的那样，你与$allSchools = mysqli_real_escape_string($row['schools']);之类的东西无关：mysqli_real_escape()在写入数据库之前仅用于，而不是在阅读之后从它！

在其他代码中使用唯一值

3 个答案: