JDBC Interview Questions and Answers
Question - 91 : - Explain JDBC Savepoint?
Answer - 91 : -
A savepoint represents a point that the current transaction can roll back to. Instead of rolling all its changes back, it can choose to roll back only some of them.
Question - 92 : - List the advantages of using DataSource?
Answer - 92 : -
Data source is dividing work among administrator and programmer/developer.
The administrator creates a DataSource object and ties up it with JNDI registry. A programmer/ developer retrieves the DataSource object from the registry. Then it will establish the connection with the database.
Question - 93 : - What is the reason why we need a JdbcRowSet like the wrapper around ResultSet?
Answer - 93 : -
We can use ResultSet object as a JavaBeans component.
- A JdbcRowSet also can be used as a JavaBeans component. That’s why it can be created and configured at design or compile time and executed at run time.
- All jdbcRowSet objects are scrollable and updatable.
Question - 94 : - How many ways that we can view a result set?
Answer - 94 : -
There are 2 ways to view ResultSet
Example: getInt(String columnName), getInt(int columnIndex)
Question - 95 : - How many ways can you update a result set?
Answer - 95 : -
Following methods helps you to update result set
- updateRow()
- deleteRow()
- refreshRow()
- cancelRowUpdates()
- insertRow()
Question - 96 : - Why should we close database connections in Java?
Answer - 96 : -
As a best practice, we must close the resultset, the statement and the connection. If the connection is coming from a pool, on closure, the connection is sent back to the pool for reuse. We are doing this in the finally{} block, because if any exception occurs, then we still get the chance to close this.
Question - 97 : - Why are we using blob datatypes in JDBC?
Answer - 97 : -
These are used to store a large amount of data into the database like images, movie, etc.
Question - 98 : - How to set the attribute Concurrency in ResultSet?
Answer - 98 : -
There are two concurrency levels
- CONCUR_READ_ONLY – It is only for reading.
- CONCUR_UPDATABLE − It is for both read and updated.
Question - 99 : - How to call Stored Procedures in JDBC?
Answer - 99 : - We can execute the SQL Stored procedures through the CallableStatement interface. The CallableStatement object can be created using the prepareCall() method of the Connection interface.
Question - 100 : - What is the ResultSet interface?
Answer - 100 : -
ResultSet interface is used to store the output data after the SQL query execution. The object of ResultSet maintains the cursor point at the result data. As a default, the cursor points before the first row of the result data. We can traverse the data in the resultset objects as well.
Syntax:
Statement Interface:
Statement stmnt1 = conn.createStatement();
ResultSet resultset = stmnt1.executeQuery(“Select * from EMPLOYEE”);
PreparedStatement Interface:
PreparedStatement pstmnt1 = conn.prepareStatement(insert_query);
ResultSet resultset = pstmnt1.executeQuery(“Select * from EMPLOYEE”);