In this article series, we will discuss different types of questions that can be asked in a Java interview, in order for the employer to test your skills in Java and object-oriented programming. This article is dedicated to the JDBC (Java Database Connectivity).
Contents
1What is JDBC?
JDBC is an abstraction layer that allows users to choose between databases. JDBC enables developers to write database applications in Java, without having to concern themselves with the underlying details of a particular database.
2Explain the role of Driver in JDBC.
The JDBC Driver provides vendor-specific implementations of the abstract classes provided by the JDBC API. Each driver must provide implementations for the following classes of the java.sql package: Connection, Statement, PreparedStatement, CallableStatement, ResultSet and Driver.
3What is the purpose Class.forName method?
This method is used to load the driver that will establish a connection to the database.
4What is the advantage of PreparedStatement over Statement?
PreparedStatements are precompiled and thus, their performance is much better. Also, PreparedStatement objects can be reused with different input values to their queries.
5What is the use of CallableStatement?
Name the method, which is used to prepare a CallableStatement. A CallableStatement is used to execute stored procedures. Stored procedures are stored and offered by a database. Stored procedures may take input values from the user and may return a result. The use of stored procedures is highly encouraged because it offers security and modularity. The method that prepares a CallableStatement is the following:
CallableStament.prepareCall();
6What does Connection pooling mean?
The interaction with a database can be costly, regarding the opening and closing of database connections. Especially, when the number of database clients increases, this cost is very high and a large number of resources is consumed. A pool of database connections is obtained at startup by the application server and is maintained in a pool. A request for a connection is served by a connection residing in the pool. At the end of the connection, the request is returned to the pool and can be used to satisfy future requests.
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