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24.5.4 The View WITH CHECK OPTION Clause
The WITH CHECK OPTION
clause can be given for
an updatable view to prevent inserts to rows for which the
WHERE
clause in the
select_statement
is not true. It also
prevents updates to rows for which the WHERE
clause is true but the update would cause it to be not true (in
other words, it prevents visible rows from being updated to
nonvisible rows).
In a WITH CHECK OPTION
clause for an updatable
view, the LOCAL
and CASCADED
keywords determine the scope of check testing when the view is
defined in terms of another view. When neither keyword is given,
the default is CASCADED
.
WITH CHECK OPTION
testing is
standard-compliant:
With
LOCAL
, the viewWHERE
clause is checked, then checking recurses to underlying views and applies the same rules.With
CASCADED
, the viewWHERE
clause is checked, then checking recurses to underlying views, addsWITH CASCADED CHECK OPTION
to them (for purposes of the check; their definitions remain unchanged), and applies the same rules.With no check option, the view
WHERE
clause is not checked, then checking recurses to underlying views, and applies the same rules.
Consider the definitions for the following table and set of views:
Here the v2
and v3
views are
defined in terms of another view, v1
.
Inserts for v2
are checked against its
LOCAL
check option, then the check recurses to
v1
and the rules are applied again. The rules
for v1
cause a check failure. The check for
v3
also fails:
Document created the 26/06/2006, last modified the 26/10/2018
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