SQL 面接の質問と回答
質問 146. What is the difference between Truncate and Delete interms of Referential Integrity?
DELETE removes one or more records in a table, checking referential Constraints (to see if there are dependent child records) and firing any DELETE triggers. In the order you are deleting (child first then parent) There will be no problems.
TRUNCATE removes ALL records in a table. It does not execute any triggers. Also, it only checks for the existence (and status) of another foreign key Pointing to the table. If one exists and is enabled, then you will get The following error. This is true even if you do the child tables first.
ORA-02266: unique/primary keys in table referenced by enabled foreign keys
You should disable the foreign key constraints in the child tables before issuing the TRUNCATE command, then re-enable them afterwards.
質問 147. What does preemptive in preemptive multitasking mean ?
Preemptive refers to the fact that each task is alloted fixed time slots and at the end of that time slot the next task is started.
質問 148. What does the OLTP stands for ?
OLTP stands for On Line Transaction Processing
質問 149. What is the most important requirement for OLTP ?
OLTP requires real time response.
質問 150. In a client server environment, what would be the major work that the client deals with ?
The client deals with the user interface part of the system.
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