Consider a database table has 6 columns attributes show the

Consider a database table has 6 columns (attributes), show the maximum number of superkeys for this table,  if the table has one candidate key (primary key).  

Solution

Answer:

Since one is candidate key,all the keys with it are super keys. if atrributes are : a,b,c,d,e,f. Suppose a is a candidate key , then ab,abc,abcd,abcde,abcdef are all super keys more ever abd ,abe,abf are also the super keys . In general it is :

2^(6 - 1) = = 32 keys.

Consider a set of keys in which one key is a primary key : { a , b, c , d , e , f }

exclude b and take number of subsets possible between b to f = 2^(6-1) = 32 . Thus there are 32 super keys.