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Q: What is referential integrity?
Answer:
RI ensures foreign key values exist in parent. CREATE TABLE child ... REFERENCES parent(key). ON DELETE CASCADE/SET NULL/RESTRICT. DB2 enforces automatically. Constraint violations return -530/-531. Design carefully.
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Q: How to write recursive CTE?
Answer:
WITH RECURSIVE cte AS (base-case UNION ALL recursive-case referencing cte) SELECT * FROM cte. For hierarchies: start with root, join to find children. DEPTH limit prevents infinite recursion.
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Q: What is CICS asynchronous processing?
Answer:
RUN TRANSID for async execution. EXEC CICS RUN TRANSID(xx) CHILD. FETCH CHILD waits for completion. Modern async pattern. Alternative to START.