I think a Junction Table would simplify this for you: http://en.wikipedia.org/wiki/Junction_table
It would look something like:
table name: user
user_id user_name
1 abc
2 xyz
3 pqr
4 new
table2 name : brackets
brackets_id bracket_name
1 bracket_1
2 bracket_2
3 bracket_3
4 bracket_4
table3 your junction table:
user_id brackets_id
1 2
1 3
2 1
2 3
2 4
etc.etc.