How to connect to database with jdbc? Steps to connect to database

How does jdbc connect to the database? What this article brings to you is how to use JDBC to connect any Java application to a database. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

There are 5 steps to connect any Java application to a database using JDBC. These steps are as follows:

1. Register Driver class

2. Create connection

3. Create statement

4. Execute query

5. Close the connection

# Let’s introduce in detail how to implement these steps.

1. Register the Driver class

The forName() method of the Class class is used to register the driver class. This method is used to dynamically load driver classes.

Syntax of forName() method

public static void forName(String className)throws ClassNotFoundException

Note: Starting with JDBC 4.0, explicitly registering the driver is optional. We just need to put the vender's Jar in the classpath, and then the JDBC driver manager can automatically detect and load the driver.

Example of registering Oracle driver class

Class.forName（“oracle.jdbc.driver.OracleDriver” ）;

2. Create connection

DriverManager class The getConnection() method is used to establish a connection with the database.

GetConnection() method syntax

Syntax 1:

 public static Connection getConnection(String url)throws SQLException

Syntax 2:

public static Connection getConnection(String url,String name,String password)  throws SQLException

Example of establishing a connection with Oracle database

Connection con=DriverManager.getConnection(  
"jdbc:oracle:thin:@localhost:1521:xe","system","password");

3. Create a Statement object

The createStatement() method of the Connection interface is used to create Statement object. The Statement object is responsible for executing queries on the database.

Syntax of createStatement() method

public Statement createStatement() throws  SQLException

Example of creating Statement object

Statement stmt=con.createStatement();

4 , Execute query

#The executeQuery() method of the Statement interface is used to execute a query to the database. This method returns an object of ResultSet which can be used to get all records of the table.

Syntax of executeQuery() method

public ResultSet executeQuery(String sql)throws SQLException

Example of executing query

ResultSet rs=stmt.executeQuery("select * from emp");  
  
while(rs.next()){  
System.out.println(rs.getInt(1)+" "+rs.getString(2));  
}

5, Close the connection object

By closing the connection object statement, the ResultSet will be automatically closed. The close() method of Connection interface is used to close the connection.

Syntax of close() method

public void close() throws SQLException

Example of closing connection

con.close();

Note: Starting from Java 7, JDBC can automatically close resources of type Connection, ResultSet and Statement using try-with-resources statement.

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