Mysql count frequency

Question

I've checked similar questions but it didnt help in my precise question. So, my table goes like this: ``` id age 1 30 2 36 3 30 4 52 5 52 6 30 7 36 ``` etc.. I need to count the frequency of ages: ``` age freq 30 2 36 3 52 2 ``` 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]}]);"; } ?> ``` The goal is build a chart

Accepted Answer

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
```

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];
}
```

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

Mysql count frequency

Solution

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