JDBC introduction

1,JDBC Concept

Java Database Connectivity(JDBC)：Java Access to the database solution .

JDBC Defines a set of interfaces , That is to access the general database API, Different database manufacturers implement these interfaces according to the characteristics of their respective databases .

JDBC You want to access different databases in the same way , Let the specific database operation have nothing to do with the implementation of the database manufacturer , Thus in

Easily switch between different databases .

2,JDBC Related class interface

        DriverManager： Driver management

        Connection： Connection interface

        Statement： Statement object interface

        ResultSet： Result set interface

3,JDBC working principle

        （1）Class.forName()                  The load driver

Class.forName("com.mysql.cj.jdbc.Driver");

        （2）DriverManager()                  obtain Connection Connect

String url = "jdbc:mysql://localhost:3306/dayone?serverTimezone=GMT";
String user = "root";
String pwd = "123456";
Connection conn = DriverManager.getConnection(url, user, pwd);

        （3） establish Statement                    perform SQL sentence

String sql = "insert into student(sname,birthday,ssex,classid) values(' Zhang San ','2022-1-1',' male ','100')";
Statement statm = conn.createStatement();

        （4） return ResultSet                      Query results   

int ret = statm.executeUpdate(sql);       // perform DML sentence （ add to , Delete , modify ）, Return value int
//ResultSet rs = stmt.executeQuery(sql);    // perform DQL sentence （ Inquire about ）, Return value ResultSet
if(ret > 0) {
	System.out.println(" Execution succeeded ");
}else {
	System.out.println(" Execution failed ");
}

        （5） Release resources

statm.close();
conn.close();