(B)0[m[4mCHANGE[m [4mRELATION[m qq> name qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk
lqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqj
mwqwqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqwqwqwqk
x tq> [4mDELETE[m [4mCONSTRAINT[m w> constraint-name qwj x x x
x x mqqqqqqqq , <qqqqqqqj x x x
x mq> relation-constraint-def qqqqqqqqqqqqqqqqqj x x
mqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqj x
lqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqqqwqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqwqqqq> . qqqk
mq> [4mDESCRIPTION[m IS /* text */ qqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqj
mqwqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqqwqk
mqqwqqwqq> [4mDEFINE[m qq> define-clause qqqwq> . qwqj x
x tqq> [4mCHANGE[m qq> change-clause qqqu x x
x mqq> [4mDELETE[m qq> field-name qqqqqqj x x
mqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqj
mqqqq> [4mEND[m qqwqqqqq>qqqqwqq> RELATION qqqqqqq> .
mq> name qqj
1 – name
The name of the relation that you want to modify.
2 – constraint-name
The name of an existing relation-specific constraint.
3 – relation-constraint-def
Using the relation-constraint-def clause you can name or specify
the type of relation-level constraints to be defined within a
specific relation definition.
(B)0[mrelation-constraint-def =
qwq> [4mCONSTRAINT[m constraint-name IS qqwqk
mqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqj x
lqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqj
twq> [4mUNIQUE[m qqqqqqw>qqw> unique-field-name qqqwqqwqqqk
xmq> [4mPRIMARY[m [4mKEY[m qj mqqqqqqqqq , qqqq<qqqqqqj x x
tqq> [4mFOREIGN[m [4mKEY[m qw> referencing-field-name qwqk x x
x mqqqqqqqqqqqqq , qqqq<qqqqqj x x x
x lqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqj x x
x mq> [4mREFERENCES[m referenced-relation-nameqqqqqqqkx x
x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqjx x
x mqqqwqqqqqqqqqqqqqqqqqqqqqqqqqqwqqqqqu x
x mw> referenced-field-name wj x x
x mqqqqqqqqqq , qqqq<qqqqqqj x x
mqqq> [4mUSING[m rse [4mREQUIRE[m conditional-expr qqqqqqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqj
mwqqqqqqqqqqqqqqqqqqqqqqqqqwq>
m> [4mCHECK[m ON qwqq> [4mCOMMIT[m qu
mqq> [4mUPDATE[m qj
3.1 – Arguments
Constraint-name must be unique within the database. The
constraint name can be referred to in other statements such as
DEFINE RELATION, SHOW CONSTRAINT, and START_TRANSACTION.
The phrase 'CONSTRAINT constraint-name is' is optional. If you
specify the keyword CONSTRAINT, you must also provide a name for
the constraint.
4 – text
A text string that adds a comment. You can apply the description
to the entire relation definition using the DESCRIPTION keyword.
You can also apply a separate description to each field using the
text markers before the DEFINE or CHANGE clause.
5 – DEFINE
Using the DEFINE option of CHANGE RELATION, you can add a
globally defined field to a relation. You can also use a local
field name to refer to that global field. You can also define a
relation-specific constraint at the field level.
(B)0[mdefine-clause = qqwqqqqqqqqqqqqqqqwqqqk
mq> /* text */ qj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqwq> global-field-name qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqk
tq> local-field-name qq> [4mBASED[m ON q> global-field-name qj x
x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
x mwqqqqqqqqqqqqqqqqqwqwqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk
x mqw> dtr-clause qwj mqqw> field-constraint-def qwqqqu
x mqqqqqq<qqqqqqqj mqqqqqqqqqq<qqqqqqqqqqqqqj x
x x
mq> local-field-name qq> [4mCOMPUTED[m [4mBY[m q> value-expr qk x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x
mqqqwqqqqqqqqqqqqqqqqqqwqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqvq>
mqw> dtr-clause qwqj
mqqqqqq<qqqqqqqj
5.1 – Arguments
The action of CHANGE RELATION with the DEFINE-CLAUSE depends on
the define-clause, as follows:
o DEFINE global-field-name-includes an existing global field
definition in the relation
If you include only a name with the DEFINE option, Oracle Rdb
searches for a field with that name in the list of global
field definitions for the database. If such a field definition
exists, Oracle Rdb adds that field definition to the relation
definition. If no field has that name, Oracle Rdb returns an
error message.
o DEFINE local-field-name BASED ON global-field-name-includes
an existing field definition in the relation, but gives it a
local name
If you include the BASED ON qualifier, Oracle Rdb uses the
definition specified by the global-field-name syntax.
However, the name of the new field in the relation is the
one specified by the local-field-name syntax. This local name
does not become part of the global list of field names for the
database.
You can specify local DATATRIEVE support clauses for the field
specified with the local-field-name syntax. If you do, this
local specification overrides the DATATRIEVE clauses attached
to the global-field-name.
o DEFINE local-field-name COMPUTED BY expression-adds a new
virtual field
The COMPUTED BY qualifier causes Oracle Rdb to calculate the
field's value at run time, based on the specified expression.
You can specify local DATATRIEVE support clauses on any of
these fields. For more information on the DATATRIEVE clauses,
ask for HELP on Field_attr.
o If you include the DEFINE CONSTRAINT clause, Oracle Rdb defines
the specified relation-specific constraint.
5.2 – field-constraint-def
Using the field-constraint-def clause you can name or specify the
type of field-level constraints to be defined within a specific
relation definition.
(B)0[mfield-constraint-def =
qwqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqk
mq> [4mCONSTRAINT[m constraint-name IS qqj x
lqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqj
mwq> [4mNOT[m [4mMISSING[m qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqk
tq> [4mUNIQUE[m qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqu x
tq> [4mPRIMARY[m [4mKEY[m qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqu x
mw> [4mREFERENCES[m referenced-relation-name qwqqqqqqqqqqqqqqqqqqqqqqqqwu x
x m> referenced-field-name jx x
x x x
mq> [4mUSING[m rse [4mREQUIRE[m conditional-expr qqqqqqqqqqqq>qqqqqqqqqqqqqqj x
x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mwqqqqqqqqqqqqqqqqqqqqqqqqqqqwq>
mqq> [4mCHECK[m ON qwqq> [4mCOMMIT[m qu
mqq> [4mUPDATE[m qj
5.2.1 – Arguments
Constraint-name must be unique within the database. The
constraint name can be referred to in other statements such as
DEFINE RELATION, SHOW CONSTRAINT, and START_TRANSACTION.
The phrase 'CONSTRAINT constraint-name is' is optional. If you
specify the keyword CONSTRAINT, you must also provide a name for
the constraint.
A field constraint definition differs from a relation constraint
definition in that you cannot repeat referenced field names. See
the "relation-constraint-def" help subtopic of CHANGE_RELATION
for more information.
6 – CHANGE
The CHANGE RELATION statement with the CHANGE option modifies the
local attributes of an existing field. Only the attributes you
specify in the statement change; all others stay as they are.
For more details, see the Arguments.
You can change relation-specific constraints using the DELETE
CONSTRAINT clause of the CHANGE option. Any constraint to be
changed must be first specifically deleted by name and then re-
declared.
(B)0[mchange-clause =
qwqqqqqqqqq>qqqqqqqqwqqqqk
mqq> /* text */ qqqj x
lqqqqqqqqqq<qqqqqqqqqqqqqj
mwqq> global-field-name qqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqwqk
tqq> local-field-name qqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqu x
mqq> local-field-name qqqqq> [4mBASED[m ON global-field-name qqqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mwqqqqqq>qqqqqqqqqwqwqwqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqwqwq>
mw> dtr-clause qwj x tq> [4mDELETE[m [4mCONSTRAINT[m qw> constraint-name qwu x
mqqqqq<qqqqqqqqj x x mqqqqqqqqq , qqqqqqqjx x
x mq> field-constraint-def qqqqqqqqqqqqqqqqqqqj x
mqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqj
6.1 – Arguments
The action of the CHANGE RELATION statement with the CHANGE
option depends on the change-clause as follows:
o CHANGE field-name BASED ON global-field-name-gives the
specified field the attributes of another field
o CHANGE field-name dtr-clause-changes DATATRIEVE support
characteristics
o DELETE CONSTRAINT constraint-name-deletes a relation-specific
constraint from the relation definition
You can specify local DATATRIEVE support clauses on any of these
fields. For more information on the DATATRIEVE clauses, ask for
HELP on Field_attr.
7 – DELETE
Deletes the field from the relation. This option deletes the
field only from the relation definition. The global field
definition by this name is still defined for the database as a
whole, and other relations can still refer to it.
If an existing view, index, constraint, or computed field refers
to the field, Oracle Rdb returns an error when you try to delete it.
(B)0[m[4mDELETE[m [4mFIELD[m qqqwqqq> field-name qqqqwqqq> .
mqqqq<qqqq , qqqq<qqqj