A su consulta SELECT le falta una cláusula GROUP BY. Probablemente te refieres a:
INSERT INTO appfilter2
SELECT userapps.name, GROUP_CONCAT(CONCAT(userapps.activity, '/',userapps.class)) AS activity
FROM userapps
GROUP BY userapps.name
A su consulta SELECT le falta una cláusula GROUP BY. Probablemente te refieres a:
INSERT INTO appfilter2
SELECT userapps.name, GROUP_CONCAT(CONCAT(userapps.activity, '/',userapps.class)) AS activity
FROM userapps
GROUP BY userapps.name