How to use MySQL for JDBC programming and addition, deletion, modification and query

Java database programming JDBC

Concept

• JDBC is a Java API used to execute sql statements. It is the database connection specification in java. This API consists of some interfaces and classes. It provides a standard API that allows Java developers to uniformly access multiple relational databases

• The essence is to implement a MySQL client through code and interact with data through the network and server. , the client cannot appear out of thin air, so the database provides a set of APIs to facilitate our implementation

• There are many types of databases, and the APIs provided by different databases are different, so java is used to solve this problem One question provides JDBC, a database operation API that comes with java. This API covers all database operation modes.

• Essentially, java itself completes the JDBC API and database API. Convert between

Use steps

to create a DataSource object. This object describes where the database server is.

DataSource dataSource = new MysqlDataSource();
		//设置数据库所在的地址
        ((MysqlDataSource)dataSource).setURL("jdbc:mysql://127.0.0.1:3306/lmp?characterEncoding=utf8&useSSL=false");
        //设置登录数据库的用户名
        ((MysqlDataSource)dataSource).setUser("root");
        //设置登录数据库的密码
        ((MysqlDataSource)dataSource).setPassword("woshizhu123");

Connect to the database through Connection (enter the password to connect successfully)

//import java.sql.Connection;
 Connection connection  = dataSource.getConnection();

Splice the sql statement (write the sql statement)

String sql = "insert into student values(1,'张三')";

Pack the sql statement into an object

PreparedStatement statement = connection.prepareStatement(sql);

Execute sql statement (press Enter to execute the sql statement)

int ret = statement.executeUpdate();

• Execute update delete insert Use executeUpdate() method

• Execute select Use executeQuery( ) Method

• Using the executeQuery() method will return a resultSet collection, including the found data. Initially, the resultSet does not point to any row of records. Use next to point it to the first record. record, and then use next to point to the next record

Release resources

 statement.close();
 connection.close();

Use JDBC to implement addition (insert)

public class TestJDBC {
    public static void main(String[] args) throws SQLException {
        Scanner scanner = new Scanner(System.in);
        DataSource dataSource = new MysqlDataSource();
        ((MysqlDataSource)dataSource).setURL("jdbc:mysql://127.0.0.1:3306/java102?characterEncoding=utf-8&useSSL=false");
        ((MysqlDataSource)dataSource).setUser("root");
        ((MysqlDataSource)dataSource).setPassword("woshizhu123");
        Connection connection = dataSource.getConnection();
        System.out.println("输入id");
        int id = scanner.nextInt();
        System.out.println("输入名字");
        String name = scanner.next();
        String sql = "insert into student values(?,?)";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setInt(1,id);
        statement.setString(2,name);
        int ret = statement.executeUpdate();
        if(ret == 1){
            System.out.println("插入成功");
        }else {
            System.out.println("插入失败");
        }
        statement.close();
        connection.close();
    }
}

Use JDBC to implement deletion (delete) )

public class TestJDBCDelete
{
    public static void main(String[] args) throws SQLException {
        DataSource dataSource = new MysqlDataSource();
        ((MysqlDataSource)dataSource).setURL("jdbc:mysql://127.0.0.1:3306/java102?characterEncoding=utf8&useSSL=false");
        ((MysqlDataSource)dataSource).setUser("root");
        ((MysqlDataSource)dataSource).setPassword("woshizhu123");
        Connection connection = dataSource.getConnection();
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要删除的id");
        int id = scanner.nextInt();
        String sql = "delete from student where id = ?";
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        preparedStatement.setInt(1,id);
        int ret = preparedStatement.executeUpdate();
        System.out.println(ret);
        preparedStatement.close();
        connection.close();
    }

Use JDBC to implement modification (update)

public class TestJDBCUpdate {
    public static void main(String[] args) throws SQLException {
        DataSource dataSource = new MysqlDataSource();
        ((MysqlDataSource)dataSource).setURL("jdbc:mysql://127.0.0.1:3306/java102?characterEncoding=utf8&useSSL=false");
        ((MysqlDataSource)dataSource).setUser("root");
        ((MysqlDataSource)dataSource).setPassword("woshizhu123");
        Connection connection = dataSource.getConnection();
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要修改的学生id");
        int id = scanner.nextInt();
        System.out.println("请输入要修改的学生姓名");
        String name = scanner.next();
        String sql = "update student set name = ? where id = ?";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setString(1,name);
        statement.setInt(2,id);
        int ret = statement.executeUpdate();
        System.out.println(ret);
        statement.close();
        connection.close();
    }
}

Use JDBC to implement search (select)

public static void testJDBCSelect() throws SQLException {
        //1创建DataSource对象
        DataSource dataSource = new MysqlDataSource();
        //2连接数据库
        ((MysqlDataSource)dataSource).setURL("jdbc:mysql://127.0.0.1:3306/java_5_31?characterEncoding=utf-8&useSSL=true");
        ((MysqlDataSource)dataSource).setUser("root");
        ((MysqlDataSource)dataSource).setPassword("listen");
        Connection connection = dataSource.getConnection();
        //3拼接sql
        String sql = "select * from student";
        PreparedStatement statement = connection.prepareStatement(sql);
        //4执行sql
        ResultSet resultSet = statement.executeQuery();
        //5遍历得到的集合
        while (resultSet.next()) {
            int id = resultSet.getInt("id");
            String name = resultSet.getString("name");
            int classId = resultSet.getInt("classId");
            System.out.println("id " + id + " name " + name + " classId " + classId);
        }
        //6关闭资源
        resultSet.close();
        statement.close();
        connection.close();
    }

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