18 Data Modification questions from the SQL bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.a statement that adds one or more new rows of data into a table
B.a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row
C.a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
D.an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
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2. Which term means: "a statement that adds one or more new rows of data into a table"?
Junior
A.DELETE
B.UPDATE
C.INSERT
D.RETURNING clause
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3. Which statement is correct?
Junior
A.INSERT — a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
B.INSERT — a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
C.INSERT — a statement that adds one or more new rows of data into a table
D.INSERT — an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
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4. What is UPDATE?
Junior
A.a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
B.a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row
C.an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
D.a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
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5. Which term means: "a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row"?
Junior
A.DELETE
B.UPSERT
C.UPDATE
D.INSERT
Answer + AI explanation with Pro
6. Which statement is correct?
Junior
A.UPDATE — a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence
B.UPDATE — a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
C.UPDATE — an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
D.UPDATE — a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row
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7. What is DELETE?
Junior
A.a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
B.a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence
C.a statement that adds one or more new rows of data into a table
D.a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
Answer + AI explanation with Pro
8. Which term means: "a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters"?
Junior
A.RETURNING clause
B.DELETE
C.UPDATE
D.INSERT
Answer + AI explanation with Pro
9. Which statement is correct?
Junior
A.DELETE — an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
B.DELETE — a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
C.DELETE — a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row
D.DELETE — a statement that adds one or more new rows of data into a table
Answer + AI explanation with Pro
10. What is UPSERT?
Mid
A.a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row
B.an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
C.a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence
D.a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
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11. Which term means: "an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL"?
Mid
A.TRUNCATE
B.DELETE
C.INSERT
D.UPSERT
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12. Which statement is correct?
Mid
A.UPSERT — a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row
B.UPSERT — a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
C.UPSERT — an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
D.UPSERT — a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
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13. What is TRUNCATE?
Mid
A.a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
B.a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
C.an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
D.a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence
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14. Which term means: "a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence"?
Mid
A.UPDATE
B.INSERT
C.UPSERT
D.TRUNCATE
Answer + AI explanation with Pro
15. Which statement is correct?
Mid
A.TRUNCATE — a statement that modifies the values of existing rows, typically restricted by a WHERE clause to avoid changing every row
B.TRUNCATE — a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence
C.TRUNCATE — an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
D.TRUNCATE — a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
Answer + AI explanation with Pro
16. What is RETURNING clause?
Senior
A.a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
B.a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
C.a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence
D.an operation that inserts a row or, when it would violate a unique key, updates the existing row instead, written as INSERT ... ON CONFLICT in Postgres or MERGE in standard SQL
Answer + AI explanation with Pro
17. Which term means: "a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert"?
Senior
A.UPDATE
B.UPSERT
C.RETURNING clause
D.INSERT
Answer + AI explanation with Pro
18. Which statement is correct?
Senior
A.RETURNING clause — a DDL statement that removes all rows from a table almost instantly without logging individual deletions, cannot be easily rolled back in many engines, and resets the identity sequence
B.RETURNING clause — a row-by-row data statement that removes selected rows, can be filtered by WHERE, is fully transactional, and does not reset identity counters
C.RETURNING clause — a Postgres feature that makes a modifying statement output the affected rows, commonly used to fetch a server-generated key right after an insert
D.RETURNING clause — a statement that adds one or more new rows of data into a table
Answer + AI explanation with Pro
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