Oracle SQL Oracle SQL DML Operations

Question 1

Which Oracle SQL statement inserts multiple rows in a single operation using a subquery?

Accepted Answer

INSERT INTO ... SELECT

Answer

INSERT INTO ... SELECT inserts all rows returned by a SELECT query into the target table in a single DML operation.

Question 2

What does the MERGE statement do in Oracle SQL?

Accepted Answer

Performs INSERT, UPDATE, or DELETE based on matching conditions in a single statement

Answer

MERGE (also called UPSERT) conditionally inserts or updates rows based on whether a match exists between source and target tables.

Question 3

Which Oracle SQL statement removes ALL rows from a table without logging individual row deletions?

Accepted Answer

TRUNCATE TABLE table

Answer

TRUNCATE TABLE removes all rows without generating individual undo records, making it much faster than DELETE but non-transactional.

Question 4

In Oracle SQL, which DML statement modifies existing rows in a table?

Accepted Answer

UPDATE

Answer

The UPDATE statement modifies values in existing rows based on a WHERE condition, affecting all rows if WHERE is omitted.

Question 5

What does the RETURNING clause do in an Oracle SQL DML statement?

Accepted Answer

Returns affected row values into a variable or bind variable

Answer

The RETURNING clause captures column values from rows affected by INSERT, UPDATE, or DELETE into variables for use in PL/SQL.

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