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
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.