Implementation of MLS/DBMS Models - Multilevel Security for Relational Databases - page 62

Get user class L(user)

Set i = 1

Pl(ti i [TC]) = L(user)

Ye s No

i = i + 1 Pl(ti i [TC]) < L(user) and

lb(C(user), ti i [TC]) = L(user)

No Ye s

t i will be updated

Set j = 1

j = j + 1

t j [PK] = t i [PK] and
Pl(ti j [PK]) = Pl(t i [PK]) and
Pl(ti i [TC]) < L(user)

No

Ye s

Insert t j in Array[t j ]

Count (Array[t j ]) = 0

Ye s No

Choose t j

Insert t' based t i

End

Figure 3.20 Flow chart for update operation in the belief-consistent model.

3.6.6 Delete Operation Procedure

The SQL statement for the delete operation is described as follows:
DELETE
FROM R
WHERE P
where R is an MLS relation and P is a delete condition that defines
the tuples that are to be deleted. If a subject with the security class