Steps Required to Connect Java Application to Database

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The following 5 steps are the basic steps involve in connecting a Java application with Database using JDBC:-

1.  Loading and registering the drivers.
2.  Creating a connection.
3.  Creating and executing the statements.
4.  Executing the ResultSet.
5.  Termination of database connection.
Steps to connect java application to databse

Loading and Registering the Driver:-
Class.forName(); is used to load the driver class.

Example to Register with MySql Driver:
Class.forName("com.mysql.jdbc.driver");
As we are working with MySql, so we will use MySql driver but we can have connections with more drivers:-

Name of the Drivers:
     MySql : com.mysql.jdbc.driver
     Oracle : oracle.jdbc.driver.oracledriver
     DB2 :  com.ibm.db2.jdbc.net.db2driver

Creating a Connection:-
getConnection() static method of DriverManager class is used to create a connection and if I say programmatically getConnection() method returns Connection interface type object.
Syntax:
getConnection(String url)
getConnection(String url, String username, String password)
getConnection(String url, Properties info)
Here url parameter specify database connectivity mechanism or database server identifier.
username and password  parameters are the username and password of database connection.

Example Establish Connection with MySql Driver:-
Connection con =
DriverManager.getConnection("jdbc:mysql://localhost/database_name","username","password");

Creating and Executing SQL Statement:-
For Creating SQL Statement:
createStatement() static method of Connection interface is used to create a SQL statement which return Statement class type reference object.

Example to create a SQL Statement:
Statement s=con.createStatement();

For Executing SQL Statement:
We have three types of statements:
1. execute() - It returns a Boolean value if a result set object can be retrieved . This method is generally used for DDL (Data Definition Language) statements. Basically, if we want a Boolean value to be returned from executing a statement (query) then we will use this method.
2. executeUpdate() - This method will return the number of rows affected by the execution of the SQL statements. Such as: insert, update or delete statements. Parameter for this method will be the query you will write for insert, update or delete for table.
3. executeQuery() - It returns a ResultSet object and generally used with the select SQL statements .
Now, this execution step is performed by our next step.

Execution of ResultSet:
Example to Execute a SQL Statement:
ResultSet rs=s.executeQuery("SELECT * FROM employee");
while(rs.next())
{
   System.out.println(rs.getString(“user_name”)+" "+rs.getString(“user_designation”));
}

Closing the Connection:
After executing SQL statement you need to close the connection and release the session. The close(); method of Connection interface is used to close the connection.
Example of Closing a Connection:-
con.close();
NOTE: We can also close our statement before closing of the connection such as:-
s.close();

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