How MySQL implements JDBC

JDBC Basics Introduction

Concept

JDBC (Java DataBase Connectivity, java database connection) is a Java API used to execute SQL statements, which can provide unification for a variety of relational databases Access, which consists of a set of classes and interfaces written in Java language.

  The JDBC specification defines the interface, and the specific implementation is implemented by major database vendors.

A specific database driver implementation is required to operate the database in Java, because JDBC is only the standard specification for Java to access the database. Each database vendor writes its own database driver based on the communication format of its database. Therefore, you only need to master the invocation of JDBC interface methods, and the database manufacturer will provide a database driver.

Essence

is actually a set of specifications (interfaces) officially provided by java. Used to help developers quickly connect different relational databases!

7 steps of JDBC

(1) Import jar package

(2) Register driver

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

Note: If you use a higher version of MySQL, you must use the com.mysql.cj.jdbc.Driver method, otherwise an error will be reported!

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

If it is a lower version, you can use com.mysql.jdbc.Driver

If you still get an error, You can add the time zone to the url!

url=jdbc:mysql://localhost:3306/Database name?serverTimezone=UTC

(3) Get the connection

String url = "jdbc:mysql://localhost:3306/db1";
Connection con = DriverManager.getConnection(url,"root","888888");

(4) Get the executor object

Statement stat = con.createStatement();

(5) Execute the sql statement and receive the return result

String sql = "SELECT * FROM user";
ResultSet rs = stat.executeQuery(sql);

(6) Processing results

while(rs.next()) {
    System.out.println( rs.getInt("id")
                + "\t" + rs.getString("name"));
}

(7) Release resources

con.close();
stat.close();
rs.close();

JDBC entry sample code

Change the user name, database name, and password in the Connection object to your own!

public class jdbc_demo01 {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        // 1.导入jar包
        // 2.注册驱动
        Class.forName("com.mysql.cj.jdbc.Driver");
 
        // 3.获取连接
        String url = "jdbc:mysql://localhost:3306/db1";
        Connection con = DriverManager.getConnection(url,"root","888888");
        // 4.获取执行者对象
        Statement stat = con.createStatement();
        // 5.执行sql语句，并且接收结果
        String sql = "SELECT * FROM product";
        ResultSet rs = stat.executeQuery(sql);
        // 6.处理结果
        while(rs.next()) {
            System.out.println( rs.getInt("id") + "\t"
                    + rs.getString("name") + "\t"
                    + rs.getInt("price") + "\t"
                    + rs.getString("brand") + "\t"
                    + rs.getInt("stock")
            );
        }
        // 7。释放资源
        con.close();
        stat.close();
        rs.close();
    }
}

The results are as follows:

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