18 real Data Modification questions from the SQL bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is INSERT?
Junior
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
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
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
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
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
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"?
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
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
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"?
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
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
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"?
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
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
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"?
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
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