The CONCAT_WS function has at least two arguments specified for it. The function uses the first argument value as the separator and returns the result.
CONCAT_WS( string1, string2 [,string3 [, ... [, stringN]...]])
string :
• character string
• NULL
SELECT CONCAT_WS(' ', 'CUBRID', '2008' , 'R3.0');
concat_ws(' ', 'CUBRID', '2008', 'R3.0')
======================
'CUBRID 2008 R3.0'
--it returns strings even if null is specified for one of parameters
SELECT CONCAT_WS(' ', 'CUBRID', '2008', NULL, 'R3.0');
concat_ws(' ', 'CUBRID', '2008', null, 'R3.0')
======================
'CUBRID 2008 R3.0'
--it converts number types and then returns concatenated strings with separator
SELECT CONCAT_WS(' ',2008, 3.0);
concat_ws(' ', 2008, 3.0)
======================
'2008 3.0'