Mysql计数频率

2021-12-30 00:00:00 frequency arrays count mysql

我检查过类似的问题，但对我的确切问题没有帮助.

I've checked similar questions but it didnt help in my precise question.

所以，我的桌子是这样的:

So, my table goes like this:

id age
1  30
2  36
3  30
4  52
5  52
6  30
7  36

等等.

我需要计算年龄的频率:

I need to count the frequency of ages:

age freq
30   2
36   3
52   2

我怎样才能抓住这个频率?在此之后，我将需要使用该数据，因此可能需要使用数组?谢谢！

How can I grab this freq? After this I will need to work with that data, so it might be necessary using array? Thanks!

function drawChart() {

      // Create the data table.

      var data = new google.visualization.DataTable();
      data.addColumn('string', 'age');
      data.addColumn('number', 'freq');

        <?php
            while($row = mysql_fetch_row($result)) 
            {
            $frequencies[$row[0]] = $frequencies[1];
            echo "data.addRow(['{$row[0]}', {$row[1]}]);";
            }

        ?>

目标是构建图表

推荐答案

你需要按共同年龄对行进行分组，然后计算每组中有多少行:

You need to group the rows by the common age, then count how many are in each group:

SELECT age, COUNT(*) AS freq FROM ages GROUP BY age

然后将其转换为数组，请在 PHP 中执行此操作:

To then convert it into an array, do this in PHP:

$frequencies = array ();
$result = mysql_query('SELECT age, COUNT(*) AS freq FROM table GROUP BY age');
if($result === false) { handle error here... }
while($row = mysql_fetch_row($result)) {
    $frequencies[$row[0]] = $row[1];
}

您现在有一个名为 $frequencies 的关联数组，其中年龄为键，频率为值.

You now have an associative array called $frequencies with the ages as keys and their frequency as values.

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