Count the rows with same ID in php

Question

I'm trying to count the rows with the same id

|curs_code|cursistnr|Mark|Payed|
    C#        20       6    50
    PHP       25       8    100
    C#        8        7    100

the output needs to be

C#, 2times

I've tried

$sql = "SELECT count(curs_code) as 'count_of_curs' FROM cursus where curs_code='$id'";
$query = $magazijn->query($sql);
return $query->fetchAll());

but gives me this output:

C#
 array (size=1)
  0 => 
   array (size=2)
    'count_of_curs' => string '1' (length=1)
  0 => string '1' (length=1)

PHP
 array (size=1)
  0 => 
   array (size=2)
    'count_of_curs' => string '1' (length=1)
  0 => string '1' (length=1)

your thought about this?

Answer 1

SELECT curs_code, count(*) as 'count_of_curs' FROM cursus where curs_code='$id' group by curs_code

Remove the where if you want the entire list.

Answer 2

It looks like the question you are asking is "Why is the expression COUNT(curs_code) returning a value of 1 when I expect a value of 2?"

I think what this means is that the two occurrences of C# that appear to be the same to you are actually different values. This is likely due to "hidden" whitespace characters in one of the values.

To return all values of curs_code that contain the string C# , and to "see" what is actually stored, run a query like this:

SELECT curs_code
     , HEX(curs_code)
     , CHAR_LENGTH(curs_code)
  FROM cursus
 WHERE curs_code LIKE '%C#%'

As a demonstration:

  SELECT cc
       , HEX(cc)
       , CHAR_LENGTH(cc)
    FROM ( SELECT 'C#' AS cc
           UNION ALL SELECT 'C#\t'
           UNION ALL SELECT 'C#\0'
         ) c  
   WHERE cc LIKE '%C#%'


  cc   HEX(cc)  CHAR_LENGTH(cc)  
  ---  -------  ---------------
  C#   4323                   2
  C#   432309                 3
  C#   432300                 3

---

If you just want to find "duplicate" values of curs_code:

  SELECT c.curs_code
       , COUNT(1) AS count_of_curs_code
    FROM cursus
   GROUP BY c.curs_code
  HAVING COUNT(1) > 1
   ORDER BY c.curs_code