What are delete-connected tables ?
Tables related with a foreign key are called delete-connected because a deletion in the primary key table can affect the contents of the foreign key table. Read more »
Archive for April, 2008
What is the self-referencing constraint ?
The self-referencing constraint limits in a single table the changes to a primary key that the related foreign key defines. The foreign key in a self referencing... Read more »
What is the cascade rule and how does it relate to deletions made with a subselect ?
The cascade rule will not allow deletions based on a subselect that references the same table from which the deletions are being made. Read more »
Under what circumstances will DB2 allow an SQL statement to update more than one primary key value at a time ?
Never. Such processing could produce duplicate values violating entity integrity. Primary keys must be updated one at a time. Read more »
If the base table underlying a view is restructured, eg. attributes are added, does the application code accessing the view need to be redone?
No. The table and its view are created anew, but the programs accessing the view do not need to be changed if the view and attributes accessed remain the same. Read more »
What is a LIKE table and how is it created ?
A LIKE table is created by using the LIKE parameter in a CREATE table statement. LIKE tables are typically created for a test environment from the production environment. Read more »