JDBC Quiz ( Intermediate ) - All Questions

This intermediate JDBC quiz is designed for developers who know basic database connectivity and want to deepen their understanding of real-world JDBC usage. It focuses on prepared statements, transactions, batch processing, ResultSet types, metadata, connection handling, and commonly asked JDBC interview scenarios.

Question 1: Why is PreparedStatement preferred over Statement in real-world applications?

It uses less memory
It prevents SQL injection and improves performance
It supports only SELECT queries
It does not require connection

Explanation: PreparedStatement improves security and performance by precompiling SQL.

Question 2: What happens when auto-commit mode is disabled?

Queries fail
Each statement is committed automatically
Transactions must be committed manually
Rollback is disabled

Explanation: Manual commit is required when auto-commit is false.

Question 3: Which JDBC method disables auto-commit mode?

disableAutoCommit()
setAutoCommit(false)
commit(false)
autoCommitOff()

Explanation: setAutoCommit(false) disables auto-commit.

Question 4: What is the main benefit of batch processing in JDBC?

Improved memory usage
Reduced network calls
Better indexing
Automatic rollback

Explanation: Batch processing reduces round trips to the database.

Question 5: Which method executes all SQL commands in a batch?

runBatch()
execute()
executeBatch()
commitBatch()

Explanation: executeBatch() runs all batched SQL statements.

Question 6: Which interface allows executing parameterized SQL queries?

Statement
PreparedStatement
CallableStatement
ResultSet

Explanation: PreparedStatement supports parameterized queries.

Question 7: Which JDBC interface is used for stored procedures?

Statement
PreparedStatement
CallableStatement
ResultSet

Explanation: CallableStatement is used to execute stored procedures.

Question 8: Which ResultSet type allows scrolling both forward and backward?

TYPE_FORWARD_ONLY
TYPE_SCROLL_INSENSITIVE
TYPE_READ_ONLY
TYPE_SIMPLE

Explanation: TYPE_SCROLL_INSENSITIVE allows bidirectional movement.

Question 9: What does TYPE_SCROLL_SENSITIVE indicate?

ResultSet cannot scroll
Reflects database changes
Ignores database changes
Read-only access

Explanation: It reflects changes made to the database.

Question 10: Which ResultSet concurrency allows updates?

CONCUR_READ_ONLY
CONCUR_UPDATABLE
TYPE_FORWARD_ONLY
TYPE_SCROLL_ONLY

Explanation: CONCUR_UPDATABLE allows modifying rows.

Question 11: What is DatabaseMetaData used for?

Query results
Column values
Database information
Transaction control

Explanation: DatabaseMetaData provides DB-level information.

Question 12: Which metadata interface provides column details?

DatabaseMetaData
ResultSetMetaData
StatementMetaData
DriverMetaData

Explanation: ResultSetMetaData provides column info.

Question 13: Which method retrieves number of columns in ResultSet?

getCount()
getColumnCount()
columnSize()
count()

Explanation: getColumnCount() returns number of columns.

Question 14: Which exception is thrown for database access errors?

IOException
ClassNotFoundException
SQLException
RuntimeException

Explanation: SQLException represents database errors.

Question 15: What is SQLWarning?

Fatal database error
Non-fatal database warning
Compilation warning
Connection error

Explanation: SQLWarning indicates non-fatal issues.

Question 16: Which method retrieves generated primary keys?

getKeys()
getGeneratedKeys()
fetchKeys()
readKeys()

Explanation: getGeneratedKeys() retrieves auto-generated keys.

Question 17: Which JDBC feature helps prevent resource leaks?

Garbage collection
Try-with-resources
Auto-commit
Batch processing

Explanation: Try-with-resources auto-closes JDBC resources.

Question 18: Which JDBC object should be closed last?

ResultSet
Statement
Connection
DriverManager

Explanation: Connection should be closed last.

Question 19: Which interface supports executing DDL statements?

ResultSet
Statement
PreparedStatement
Both B and C

Explanation: Both Statement and PreparedStatement can execute DDL.

Question 20: Which JDBC method executes DML statements?

execute()
executeQuery()
executeUpdate()
runUpdate()

Explanation: executeUpdate() runs INSERT, UPDATE, DELETE.

Question 21: What is connection pooling?

Creating multiple databases
Reusing database connections
Caching query results
Batching SQL statements

Explanation: Connection pooling reuses connections to improve performance.

Question 22: Which benefit does connection pooling provide?

Reduced memory usage
Faster connection creation
Better indexing
Improved SQL syntax

Explanation: Pooling avoids costly connection creation.

Question 23: Which JDBC API supports batch updates?

Statement only
PreparedStatement only
Both Statement and PreparedStatement
ResultSet

Explanation: Both support batch updates.

Question 24: Which method adds SQL to a batch?

addQuery()
addBatch()
appendBatch()
queueBatch()

Explanation: addBatch() queues SQL statements.

Question 25: Which JDBC driver type is most commonly used today?

Type 1
Type 2
Type 3
Type 4

Explanation: Type 4 is pure Java and widely used.

Question 26: Why is Type 1 driver rarely used?

Low performance
Security issues
ODBC dependency
No transaction support

Explanation: Type 1 depends on ODBC drivers.

Question 27: What does commit() do in JDBC?

Undo changes
Save changes permanently
Close connection
Reset transaction

Explanation: commit() saves transaction changes.

Question 28: What happens if rollback() is called?

Transaction is saved
Transaction is ignored
Uncommitted changes are undone
Connection closes

Explanation: rollback() undoes uncommitted changes.

Question 29: Which JDBC feature ensures atomicity?

Auto-commit
Transactions
Batch processing
Indexes

Explanation: Transactions ensure atomicity.

Question 30: Which method sets query timeout?

setTimeout()
setQueryTimeout()
timeout()
queryTimeout()

Explanation: setQueryTimeout() sets execution limit.

Question 31: Which interface allows retrieving warnings?

Connection
Statement
ResultSet
All of the above

Explanation: All JDBC objects can return warnings.

Question 32: Which method clears batch statements?

resetBatch()
clear()
clearBatch()
removeBatch()

Explanation: clearBatch() removes batched commands.

Question 33: Which method checks if ResultSet is empty?

isEmpty()
next()
first()
wasNull()

Explanation: Calling next() checks for data.

Question 34: Which JDBC object controls transaction boundaries?

Statement
ResultSet
Connection
Driver

Explanation: Connection manages transactions.

Question 35: Which interface supports scrollable and updatable results?

Statement
PreparedStatement
ResultSet
Connection

Explanation: ResultSet supports scrolling and updating.

Question 36: Which method retrieves column name from metadata?

getName()
getColumnLabel()
getColumnName()
getLabel()

Explanation: getColumnName() returns column name.

Question 37: Which JDBC feature improves performance in large inserts?

Transactions
Batch processing
Indexes
Metadata

Explanation: Batch processing speeds bulk inserts.

Question 38: Which method closes all JDBC resources automatically?

finally block
try-with-resources
autoClose()
System.gc()

Explanation: Try-with-resources closes resources automatically.

Question 39: Which JDBC object represents database session?

Driver
Connection
Statement
ResultSet

Explanation: Connection represents DB session.

Question 40: Which JDBC feature improves security most?

Statements
PreparedStatements
Transactions
Indexes

Explanation: PreparedStatements prevent SQL injection.

Question 41: Which method retrieves update count?

getCount()
getUpdateCount()
count()
rows()

Explanation: getUpdateCount() returns affected rows.

Question 42: Which JDBC object executes SQL on DB server?

Connection
Statement
ResultSet
Driver

Explanation: Statement sends SQL to database.

Question 43: Which interface is parent of all JDBC exceptions?

Exception
Throwable
SQLException
RuntimeException

Explanation: SQLException is the root JDBC exception.

Question 44: Which JDBC feature handles large objects (LOBs)?

Clob and Blob
ResultSet
Metadata
Driver

Explanation: CLOB and BLOB handle large data.

Question 45: Which method retrieves binary data?

getString()
getBytes()
getBinary()
getObject()

Explanation: getBytes() retrieves binary data.

Question 46: Which JDBC object should be reused for performance?

ResultSet
Statement
PreparedStatement
DriverManager

Explanation: PreparedStatement can be reused.

Question 47: Which feature ensures consistency in JDBC transactions?

Batching
ACID properties
Indexes
Auto-commit

Explanation: ACID ensures consistency.

Question 48: What is the main goal of JDBC in applications?

Database optimization
Java-database communication
Query caching
Connection monitoring

Explanation: JDBC enables Java and database interaction.

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JDBC Quiz ( Intermediate )

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