(B)0[m[4mDEFINE[m [4mCONSTRAINT[m qqqqq> name qqqqk
lqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqqqwqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqqqk
mq> [4mDESCRIPTION[m IS /* text */ qqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqq [4mFOR[m qqq> rse qqqk
lqqqqqqqqqqqqqqqqqqqqj
mqq> [4mREQUIRE[m qqq> conditional-expr qqqqqqk
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqqqwqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqqqq> .
mq> [4mCHECK[m ON qqwqqq> [4mCOMMIT[m qqwqqj
mqqq> [4mUPDATE[m qqj
1 – name
The name of the constraint that you can refer to in other
statements. When choosing a name, follow these rules:
o Use a name that is unique among all constraint names.
o Use any valid OpenVMS name. However, the name cannot end in a
dollar sign ($) or underscore (_).
o Do not use any Oracle Rdb reserved words.
2 – text
A text string that adds a comment to the field definition. 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, CHANGE, or DELETE clause.
3 – rse
A record selection expression that defines which records of which
relations the constraint applies to.
4 – conditional-expression
A conditional expression that describes the constraint to be
placed on the records and relations defined by the RSE. For more
information on Oracle Rdb conditional expressions, ask for HELP on
Cond_expr.
5 – CHECK
Specifies whether the constraint is to be evaluated when you
issue a statement such as STORE or MODIFY that updates the
relation (UPDATE), or when you issue the COMMIT statement to
write the change to the database (COMMIT). You can override this
qualifier with the EVALUATING clause of the START_TRANSACTION
statement. The default is UPDATE.