How to use JDBC to operate database

With Mysql For example , Let's see Java How to link with the database

1. Import database driver jar package

The first step is to download a mysql Database driver for jar package , similar mysql-connector-java-5.1.20-bin.jar. Create a new one JAVA project , Create a... Under the project lib Folder , Will drive jar File copy to lib In the folder .
Then you need to put this JAR Package added to project's build path variable . Right mouse button -build path->configure build path … Click... In the pop-up interface Add jars Select drive jar Package add it to build path variable .

2. Registration drive

Imported driver , Then you need to register the driver in the program , This means that the program can operate the database corresponding to this driver .

	Class.forName(driver);

This sentence will be abnormal , Then the processing method is very simple , Just throw an exception when defining the class , perhaps try/catch Can
Just like this.

public void QueeyAll() throws Exception{
    }

3. Get database connection object Connection

The connection object is java Bridge between code and database , Through this connection object （ bridge ） Connect to database .

	String driver = "com.mysql.jdbc.Driver";//MySQL Driver name of the database 
    String url = "jdbc:mysql://localhost:3306/oldsix?useUnicode=true&characterEncoding=utf- 8&useSSL=false";// Database connection string 
    String user = "root";// user name 
    String password = "******";// password 
	Connection conn = DriverManager.getConnection(url,user,password);

The user name and password are the account and password of the database you use

4. Definition SQL sentence

Connected to the database , Is to operate the database . So define SQL sentence , In fact, it's what you want to do with the database , Put it in SQL In the sentence （ An incompletely correct metaphor ,SQL Statements are containers for operations on databases ）.
For example, I want to query user All the data in the table

		ResultSet result = null;
		String sql = "select * from user";
        result = stmt.executeQuery(sql);

5. Access to perform SQL Object of statement Statement

Define the operations to be performed on the database , Then who will help me execute ？—— perform SQL Object of statement Statement. So get this object .

		Statement stmt = null;
		stmt = conn.createStatement();

6. perform SQL, Receive the returned result , Processing return results

With the execution object, you can start to perform operations on the database , And return the operation result . The user processes the returned results

		ResultSet result = null;
		result = stmt.executeQuery(sql);

7. Release resources

After performing a series of operations , Then release resources . It's equivalent to someone working for you , When you're done , Let others go .

		result.close();
        stmt.close();
        conn.close();

After finishing these tasks, we can operate the database