What character is VALUE_SEPARATOR?
In fact, if you use HEX() function, you can guess it's the ASCII code 01 which is not really readable :

MySQL&gt; SELECT substring(besoins_sp__114, 1,1) 
       FROM civicrm_value_besoins_sp_cifiques_v_nements_26 LIMIT 1;
+---------------------------------+
| substring(besoins_sp__114, 1,1) |
+---------------------------------+
|                                |
+---------------------------------+
1 row in set (0.00 sec)

MySQL&gt; SELECT HEX(substring(besoins_sp__114, 1,1)) 
       FROM civicrm_value_besoins_sp_cifiques_v_nements_26 LIMIT 1;
+--------------------------------------+
| HEX(substring(besoins_sp__114, 1,1)) |
+--------------------------------------+
| 01                                   |
+--------------------------------------+
1 row in set (0.00 sec)


From there, you can do reverse operation using UNHEX.
So, if you need to replace this char by another more readable one, you can do the following :

MySQL&gt; SELECT replace(besoins_sp__114, UNHEX(01), '|') AS special_needs
       FROM civicrm_value_besoins_sp_cifiques_v_nements_26;
+---------------+
| special_needs |
+---------------+
| |AL|          |
| |AL|          |
| |VG|          |
| |VG|          |
| |VG|          |
| |VG|          |
| |VG|          |
| |VG|          |
| |VG|          |
| |VG|AL|       |
+---------------+