Jdbc Interview Questions Part1

6. What are four types of JDBC driver?
1. Type 1 Drivers
Bridge drivers such as the jdbc-odbc bridge. They rely on an intermediary such as ODBC to transfer the SQL calls to the database and also often rely on native code.
2. Type 2 Drivers
Use the existing database API to communicate with the database on the client. Faster than Type 1, but need native code and require additional permissions to work in an applet. Good for client-side connection.
3. Type 3 Drivers
Call the database API on the server.Flexible. Pure Java and no native code.
4. Type 4 Drivers
The hightest level of driver reimplements the database network API in Java. No native code.
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7. What packages are used by JDBC?
There are at least 8 packages:
0. java.sql.Driver
1. Connection
2. Statement
3. PreparedStatement
4. CallableStatement
5. ResultSet
6. ResultSetMetaData
7. DatabaseMetaData
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8. There are three basic types of SQL statements, what are they?
0. Statement
1. callableStatement
2. PreparedStatement
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9. What are the flow statements of JDBC?
A URL string -->getConnection-->DriverManager-->Driver-->Connection-->Statement-->executeQuery-->ResultSet.
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10. What are the steps involved in establishing a connection?
This involves two steps: (1) loading the driver and (2) making the connection.
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11. How can you load the drivers?
Loading the driver or drivers you want to use is very simple and involves just one line of code. If, for example, you want to use the JDBC-ODBC Bridge driver, the following code will load it:
Eg.
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Your driver documentation will give you the class name to use. For instance, if the class name is jdbc.DriverXYZ , you would load the driver with the following line of code:
E.g.
Class.forName("jdbc.DriverXYZ");
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12. What Class.forName will do while loading drivers?
It is used to create an instance of a driver and register it with the DriverManager. When you have loaded a driver, it is available for making a connection with a DBMS.
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13. How can you make the connection?
In establishing a connection is to have the appropriate driver connect to the DBMS. The following line of code illustrates the general idea:
E.g.
String url = "jdbc:odbc:Fred";
Connection con = DriverManager.getConnection(url, "Fernanda", "J8");
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14. How can you create JDBC statements?
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. For a SELECT statement, the method to use is executeQuery. For statements that create or modify tables, the method to use is executeUpdate. E.g. It takes an instance of an active connection to create a Statement object. In the following example, we use our Connection object con to create the Statement object stmt :
Statement stmt = con.createStatement();
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