•Each transaction can be written on the assumption that
all integrity constraints
hold in the data, before the transaction runs
•It must make sure that its changes leave the integrity constraints still holding
–However, there are allowed to be intermediate states
where the constraints do not
hold
•A transaction that does this, is called consistent
•This is an obligation on the programmer
–Usually the organization has a testing/checking and
sign-off mechanism before an
application program is allowed to get installed in the production system