usergroup permission based SQL query

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in a custom page...

i hav to use this:

$query = "SELECT * FROM " . TABLE_PREFIX . "vbtable WHERE cID = ??? ORDER BY dateline DESC";

in the category table (in mysql) there are six categories.... (cID = 1,2,3,4,5,6) & each category has specific usergroup based permission.
Like only admin group can view content of category 4 (cID=4; cPermission=6)

now i want that query, check if the current user is belong to usergroup-6 (admin)....if so it will get row from mysql table whos cID is 4....otherwise it will skip those row.