JDBC connection database

JDBC

JDBC refer to Java Database connection , It's a standard Java Application programming interface , Each database vendor needs to implement this set of interfaces , We just need to call to use Java Connect to database .

Download the driver package

Download at ：https://downloads.mysql.com/archives/c-j/

After downloading , Unzip it .
There are two types of drives ： The old version ：mysql-connector-java-5.1.46-bin.jar;
The new version ：mysql-connector-java-8.0.11.jar.
Different versions of drivers are different when connecting to the database . The old version of the driver name is ：com.mysql.jdbc.Driver; The driver name of the new version is com.mysql.cj.jdbc.Driver.

Drive configuration

（1） Create a new one under the current project lib Folder , Will drive jar The package is in this directory

（2） Right click drive jar package , Add it to the path

After the configuration is successful, it displays ：

Connect to database test

stay MySQL Create a database in the database , And create a table to test .
The code is as follows ：

package dbtest;
import java.sql.*;

public class MySQLDemo {
    
	// Statement JDBC Driver name and database URL
	static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; // Set according to different version numbers 
	static final String DB_URL = "jdbc:mysql://localhost:3306/runoob?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC&characterEncoding=UTF-8";
	// Declare the user and password of the database 
	static final String USER = "root";
	static final String PASSWORD = "123456";
	public static void main(String[] args){
    
		Connection conn = null;
		Statement stmt = null;
		try{
    
			// register JDBC drive 
			Class.forName(JDBC_DRIVER);
			// Connect to database 
			System.out.println(" Connecting to database .....");
			conn = DriverManager.getConnection(DB_URL,USER,PASSWORD);
			// Execution insert 
			System.out.println(" Execution insert ......");
			stmt = conn.createStatement();
			//SQL Insert statement 
			String sql = "INSERT INTO websites VALUES ('2', ' TaoBao ', 'https://www.taobao.com/', '13', 'CN')";
			stmt.execute(sql); // perform 
			// Close after execution 
			stmt.close();
			conn.close();
		}catch(SQLException se){
    
			// Handle SQL abnormal 
			se.printStackTrace();
		}catch(Exception e){
    
			e.printStackTrace();
		}finally{
    
			
			try{
    
				if(stmt!=null) stmt.close();
				if(conn!=null) conn.close();
			}catch(SQLException se2){
    
				se2.printStackTrace();
			}
		}
		System.out.println(" Insert a piece of data ！");
	}
}

Mistakes encountered ：
Because the coding of the database is inconsistent , So when inserting Chinese into the database, there is garbled code .
By command show variables like ‘character%’; View the encoding of the database .

Can pass set character_set_xxxx=utf8 Order to modify , But this modification is in mysql It won't work after restarting .

Therefore, it is recommended to modify the character code mysql Configuration file for ,windows Next is my.ini file ,linux Next is my.conf file , And then restart mysql The server takes effect .