Technical data

Figure 6–4 After Modifying MEMBER_B and Using RETAINING

SORT−OWNER

MEMBER−A KEY 1 MEMBER−D KEY 9

MEMBER−B KEY 8

POSTION VACATED

BY MEMBER−B

(CURRENT OF SET)

MEMBER−C KEY 6

ZK−1512−GE

If MEMBER_B’s key was changed to KEY 4, the record’s position in the set

occurrence would not change, and a FETCH NEXT WITHIN SORT_SET would

fetch MEMBER_C.

6.6 CONNECT and DISCONNECT

When the set membership class is MANUAL, use the CONNECT statement

to link a member record to its set occurrence. You can also use CONNECT for

AUTOMATIC sets, provided that the retention class is OPTIONAL and you have

disconnected the record.

When you use the CONNECT statement, specify the set or sets where the record

is to be connected. Executing a CONNECT statement without the set list clause

connects the record to all sets in which it can be, but is not yet, a member.

Before you execute a CONNECT statement, be sure that currency for the

speciﬁed set type points to the correct set occurrence. If not, the member record

will participate in the wrong set occurrence. (For more information on currency,

see Section 5.13 and Section 5.14.) You cannot execute a CONNECT for a record

that participates as an owner of the speciﬁed set.

If the set retention class is OPTIONAL, use the DISCONNECT statement to

remove a member record from a speciﬁed set. The DISCONNECT statement does

not delete a record from the database.

When you use the DISCONNECT statement, specify the sets from which the

record will be disconnected. Executing a DISCONNECT without the set list

clause disconnects the record from all the sets in which it participates as

an optional member. You cannot execute a DISCONNECT for a record that

participates as an owner of the speciﬁed set or that has a set retention class of

FIXED or MANDATORY. Refer to the Section 4.7 for an explanation of how set

membership class affects certain DML verbs.

6–8 DML Programming—Tips and Techniques