计算列中每行的相同值

Question

在我的sql中，我有一个如下表。在那个表中我有topicID，它不是主键，只是为了说清楚。我正在努力编写一个可以在表中给出相同topicID计数的脚本。

if ($result['success'] == 1) { 

$webmaster_email = "tutorial@androidstackoverflow.com";

$feedback_page = "contact-mail.php";
$error_page = "error_message.html";
$thankyou_page = "thank_you.html";

$email = $_REQUEST['email'] ;
$message = $_REQUEST['message'] ;
$message = strip_tags($message);
$message = preg_replace("/[^a-zA-Z0-9\s]/", "", $message);
$name = $_REQUEST['name'] ;
$msg = 
"Name: " . $name . "\r\n" . 
"Email: " . $email . "\r\n" . 
"Message: " . $message = wordwrap($message, 70, "\n", true);

例如：

topicID  |  description |  date     |
|  1     |    xyz      | 2018-11-11 |
|  1     |    xyz      | 2018-11-11 | 
|  2     |    xyz      | 2018-11-11 |
|  1     |    xyz      | 2018-11-11 | 
|  3     |    xyz      | 2018-11-11 |
|  3     |    xyz      | 2018-11-11 | 
|  2     |    xyz      | 2018-11-11 |
|  1     |    xyz      | 2018-11-11 | 

Answer 1

你需要的是Group BY表达。请尝试以下方法，

 select topicId as 'Topic Id' ,count(*) as 'Number of times' from my_table group by topicId