JDBC Interview Question

What's the difference between TYPE_SCROLL_INSENSITIVE , and TYPE_SCROLL_SENSITIVE?

You will get a scrollable ResultSet object if you specify one of these ResultSet constants.The difference between the two has to do with whether a result set reflects changes that are made to it while it is open and whether certain methods can be called to detect these changes. Generally speaking, a result set that is TYPE_SCROLL_INSENSITIVE does not reflect changes made while it is still open and one that is TYPE_SCROLL_SENSITIVE does. All three types of result sets will make changes visible if they are closed and then reopened:

Statement stmt =
con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
ResultSet srs =
stmt.executeQuery("SELECT COF_NAME, PRICE FROM COFFEES");
srs.afterLast();
while (srs.previous())
{
String name = srs.getString("COF_NAME");
float price = srs.getFloat("PRICE");
System.out.println(name + " " + price);
}

How to Make Updates to Updatable Result Sets?

Another new feature in the JDBC 2.0 API is the ability to update rows in a result set using methods in the Java programming language rather than having to send an SQL command. But before you can take advantage of this capability, you need to create a ResultSet object that is updatable. In order to do this, you supply the ResultSet constant CONCUR_UPDATABLE to the createStatement method.

Connection con =
DriverManager.getConnection("jdbc:mySubprotocol:mySubName");
Statement stmt =
con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
ResultSet uprs =
stmt.executeQuery("SELECT COF_NAME, PRICE FROM COFFEES");

What are batch updates?

In the java if you want to execute a set of statements, i.e. SQL statements at a time then we use batch update statement.

resultset=pst.batchUpdate();

What are the three statements in JDBC & differences between them?

Statement

Represents a basic SQL statement

PreparedStatement

Represents a precompiled SQL statement, which can offer improved performance

CallableStatement

Allows JDBC programs complete access to stored procedures within the database itself

How to call a Stored Procedure from JDBC?

he first step is to create a CallableStatement object. As with Statement an and PreparedStatement objects, this is done with an open Connection object. A CallableStatement object contains a call to a stored procedure.

E.g.

CallableStatement cs = con.prepareCall("{call SHOW_SUPPLIERS}");
ResultSet rs = cs.executeQuery();