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dealing with composite primary keys

P: 52
hi,

i have two tables:

table1: mid,name [ here, mid is the primary key ]
table2: mid,did,location [ here, mid&did is the composite primary key
also, mid references mid in table1 ]

now, i need to increment [did] against a particular mid value....
how can that be done?
please help.

i have created my tables this way....is this correct?

T1: create table t1(mid number(2) primary key, name varchar2(20));


T2: create table t2(mid number(12),did number(3),location varchar2(1000) not null, PRIMARY KEY(mid,did),
constraint me_id foreign key(mid) references t1(mid));

please help.
Mar 22 '07 #1
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P: 24
see if it works or not, i am not sure, if it does not, try to play with it, you will succeed, i won't test the code here...

CREATE SEQUENCE sequence_name
INCREMENT BY your_desired_value
START WITH value_you_want_to_start_with
MAXVALUE maximum_value
NOCYCLE;

and then use that sequence with the help of a trigger to put into your did field-

BEGIN
SELECT sequence_name.nextval
INTO :T2.did
FROM dual;
END;

cheers!
Mar 25 '07 #2

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