如果字段重复，Php sql 只回显一行

Question

假设我有一个名为 managers 的表，其中包含 3 个字段并且有 10 行。

id        AgeGroup    name
1         a           1
2         a           2
3         a           3
4         b           4
5         b           5
6         c           6
7         d           7
8         d           8
9         d           9
10        e           10

代码:

$con = mysql_connect("localhost","username","password");
if (!$con) {
    die('Could not connect: ' . mysql_error());
}

mysql_select_db("dbname", $con);
$query = "SELECT * FROM managers ORDER BY AgeGroup ASC"; 
$result = mysql_query($query) or die ("Error in query: $query. ".mysql_error());    

echo'<ul>';
if (mysql_num_rows($result)>0) {    
    while($row = mysql_fetch_array($result)) { 
        echo'<li>'.$row['AgeGroup'].'</li>';
    } 
} 
echo'</ul>';

我希望能够回应年龄组字段但没有重复。 即输出将是:

a
b 
c 
d 
e

任何帮助将不胜感激

Answer 1

添加GROUP BY查询中的子句。

$query = "SELECT * FROM managers GROUP BY AgeGroup  ORDER BY AgeGroup ASC";