Interview Questions

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Java Interview questions part 3

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Part 1 | Part 2 | Part 3 | Part 4 | Part 5 <<Previous  Next>>

Question - Define JDBC. 

Answer
The JDBC API defines interfaces and classes for making database connections. Using JDBC, you can send SQL, PL/SQL statements to almost any relational database.

Question - Describe JDBC Architecture in brief.

Answer
Java application calls the JDBC library that loads a driver which talks to the database. 

Question - Define ResultSet. 

Answer
ResultSet provides access to the rows of table. A ResultSet maintains a cursor pointing to its current row of data. The next() method is used to step through the rows of the ResultSet. 

Question - What is ResultSetMetaData? 

Answer
ResultSetMetaData Interface holds information about the columns in a ResultSet.

Question - What are the types of JDBC drivers? 

Answer
There are four types of JDBC drivers. 

JDBC-ODBC bridge plus ODBC driver, also called Type 1. 
Native-API, partly Java driver, also called Type 2. 
JDBC-Net, pure Java driver, also called Type 3. 
Native-protocol, pure Java driver, also called Type 4  

Question - Define Isolation.  

Answer
Isolation ensures one transaction does not interfere with another. The isolation helps when there are concurrent transactions. In order to set the isolation level for a JDBC transaction, we can use
Connection.setTransaction(int level) method 

Question - What are the Transaction levels available?   

Answer
TRANSACTION_NONE
TRANSACTION_READ_UNCOMMITED
TRANSACTION_READ_COMMITTED
TRANSACTION_REPEATABLE_READ
TRANSACTION_SERIALIZABLE

Question - What is the purpose of setAutoCommit do?   

Answer
A connection is in auto-commit mode by default which means every SQL statement is treated as a transaction and will be automatically committed after it is executed. If you want all statements not to be committed until you call the method commit explicitly, you need to disable auto-commit mode. 

con.setAutoCommit(false); 

Question - What is JDBC driver? 

Answer
The JDBC Driver provided by the JDBC API, is a vendor-specific implementations of the abstract classes. The driver is used to connect to the database.    

Part 1 | Part 2 | Part 3 | Part 4 | Part 5