Database Reference
In-Depth Information
6.4.1 he INSERT Statement
The INSERT statement executed by a user with security level L (user)
has the following general form [81]:
INSERT INTO R [A 1 , A 2 , ...,A n ]
VALUES [a 1 , a 2 , ..., a n ]
R is the relation name and [ A 1 , A 2 , ..., A n ] are the attribute names.
K Ci is the symmetric encryption key associated to the security level of
the user. E ( K , a i ) is the encryption of data value a i by an encryption
key. Each INSERT data manipulation can insert, at most, one tuple
into the relation R. The inserted tuple t is constructed as follows:
For 1≤i≤n
If (A i R[A i ] * )
{
Ci = L(user)
K = KCi
t[A i ] = E(K,a i )
}
Else
{
t[A i ] = null
}
t[TC] = L
i = i+1
Insert new tuple t into the multilevel relational database.
The insertion is permitted if the database state satisfies the entity
integrity, the foreign key integrity, and the referential integrity properties.
6.4.2 he DELETE Statement
The DELETE statement executed by a user with security class level
L has the following general form [82]:
DELETE FROM R
WHERE P
where R is the relation name, assuming that relation R has attributes
[A 1 ,A 2 ,...,A n ] , r is the database relation instance, and P is a predicate
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