Nested query-mysql nested query data loss

The following is an example of data loss during mysql nested query last week: Case 1: selectgroup_concat (p. prod_noseparator & #39;, & #39;) prod_nofromcore_request_prod Case 2: select * from (selectgroup_concat (p. prod_noseparator & #39;, & #39;) prod_nofromcore_request_prod) d Case 1: You can find all the data (a lot of data ...) Case 2 nested query of mysql database

The following is an example of data loss during mysql nested query last week:
Case 1:
Select group_concat (p. prod_no separator ',') prod_no
From core_request_prod

Case 2:
Select * from
(Select group_concat (p. prod_no separator ',') prod_no
From core_request_prod) d

Case 1: You can find all the data (a lot of data ...) In case 2, only part of the data can be found, and a lot of data is intercepted or lost.

Mysql 5.5.37

Explanations