Question

If a DBMS enforces a UPDATE RESTRICT option on the referential integrity constraint between CLIENT and AGENT in the HAPPY INSURANCE database, what will be the outcome after a user tries to change the AgentID value in the last record to A5

Answer 1

1. Value A4 appears once in column AgentID in AGENT, and value A4 appears once in column ClientAgent in table CLIENT

Step-by-step explanation:

In a DBMS, ON UPDATE RESTRICT means the UPDATE on the main record will fail.

If an update restrict rule is defined, an attempt to add a row to a table containing a foreign key causes the database engine to compare the value in the foreign key field to the values in the primary key. If there is no primary key row with the same value, the new row is not permitted to be added to the foreign key table.

So making a change to the record A5 will cause the Value A4 appears once in column AgentID in AGENT, and value A4 appears once in column ClientAgent in table CLIENT

A restrict rule is a rule in which the database decides whether or not to permit the desired operation based on existing values in the database.

The options to the question are:

1. Value A4 appears once in column AgentID in AGENT, and value A4 appears once in column ClientAgent in table CLIENT

2. Value A5 appears once in column AgentID in AGENT, and value A5 appears once in column ClientAgent in table CLIENT

3. Value A5 appears once in column AgentID in AGENT, and value A5 does not appear in column ClientAgent in table CLIENT

4. Value A5 does not appear in column AgentID in AGENT, and value A5 appears once in column ClientAgent in table CLIENT

The correct answer is Value A4 appears once in column AgentID in AGENT, and value A4 appears once in column ClientAgent in table CLIENT