Database access control deals with controlling who (a person or a certain computer program) is allowed to access what information in the database. The information may comprise specific database objects (e.g., record types, specific records, data structures), certain computations over certain objects (e.g., query types, or specific queries), or utilizing specific access paths to the former (e.g., using specific indexes or other data structures to access information). Database access controls are set by special authorized (by the database owner) personnel that uses dedicated protected security DBMS interfaces.
What does database access limit?
who (a person or a certain computer program) is allowed to access what information

Two groups G and H are called isomorphic if there exist group homomorphisms a: G → H and b: H → G, such that applying the two functions one after another in each of the two possible orders gives the identity functions of G and H. That is, a(b(h)) = h and b(a(g)) = g for any g in G and h in H. From an abstract point of view, isomorphic groups carry the same information. For example, proving that g • g = 1G for some element g of G is equivalent to proving that a(g) ∗ a(g) = 1H, because applying a to the first equality yields the second, and applying b to the second gives back the first.
How can showing the second equality yields the first prove the concept of isomorphic groups?
applying a to the first equality yields the second

Various ecumenical movements have attempted cooperation or reorganization of the various divided Protestant denominations, according to various models of union, but divisions continue to outpace unions, as there is no overarching authority to which any of the churches owe allegiance, which can authoritatively define the faith. Most denominations share common beliefs in the major aspects of the Christian faith while differing in many secondary doctrines, although what is major and what is secondary is a matter of idiosyncratic belief.
What types of doctrines do denominations not agree on?
secondary