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hello
i am a new user of SQL and Oracle8i at learning stage.i am facing difficulty with foreign key constraint.I make two tables one is 'master' in which field 'roll_no' has primary key then in second table 'fee' again 'roll_no' field (with same datatype and size) is defined as column level foreign key.i want to assign one more field in table 'master' as primary key for which i tried to execute following comman
ALTER TABLE master ADD primary key(house_no);
with the execution of this command i got the following message:
"table can have only one primary key"
i tried to remove primary key but it was referenced by some foriegn keys.then i tried to removr foreign key but no command run successfully and i tried to voilate the foreign key constraint and used the constraint shown by message to drop foreign key with following command:
"alter table fee drop constraint school.sys_c001262;"
but unsuccessful.Error message was
"Invalid alter table option"
please suggest me how can i solve this problem and can add one more primary key in master table and how can i remove foriegn key.Any help will be highly appreciated
Summi
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Hi,
If you have a composite primary key, then you have to drop the PK you have created and after
alter table XXXX add primary key (column1,column2 ...,columnN);
Hope that helps
Angel
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