ET @sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(' sum (case when DATE_FORMAT(message_accepted_by_signalmash, '%d')= ''',da,
''' then msg_count else 0 end ) AS `',da,'`')
)INTO @sql
FROM(SELECT DATE_FORMAT(message_accepted_by_signalmash, '%d')AS da FROM mdr m )d;
SELECT @sql;
SET @sql = CONCAT('SELECT u.username, ' , @sql, '
from mdr m ',
'join user u',
'on u.iduser = m.iduser',
'group by u.username');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
what's wrong in this query?
error:-Incorrect parameters in the call to native function 'CONCAT'