JDBC Questions et reponses d'entretien

Question 6. How can you make the connection?

To establish a connection you need to have the appropriate driver connect to the DBMS.

String url = "jdbc:odbc:WithoutBook";

Connection con = DriverManager.getConnection(url, "Username", "Password");

Question 7. How can you create JDBC statements and what are they?

A Statement object is what sends your SQL statement to the DBMS. You simply create a Statement object and then execute it, supplying the appropriate execute method with the SQL statement you want to send.

Statement stmt = con.createStatement();

Question 8. How can you retrieve data from the ResultSet?

JDBC returns results in a ResultSet object, so we need to declare an instance of the class ResultSet to hold our results. The following code demonstrates declaring the ResultSet object:
ResultSet rs = stmt.executeQuery("SELECT NAME,SAL FROM EMPLOYEE");
String s = rs.getString("NAME");
The method getString is invoked on the ResultSet object (rs), so getString() will retrieve (get) the value stored in the column NAME in the current row of rs. Note: rs is ResultSet variable name here.

Question 9. What are the different types of Statements?

• Regular statement (use createStatement method)
• prepared statement (use prepareStatement method)
• callable statement (use prepareCall)

Question 10. How can you use PreparedStatement?

This special type of statement is derived from class Statement. If you need a Statement object to execute many times, it will normally make sense to use a PreparedStatement object instead.