JDBC -数据库导入-第二版-2023-2-25

1、配置资源文件 .properties (driver, url,username,password) 便于后期更改

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/shop?useUnicode=true&characterEncoding=utf8&useSSL=false
username=root
password=123456

2、编写utils 工具类，读取配置资源，加载数据库 ，关闭资源这些操作只要连接上了，基本上不需要再重复写代码。

package JavaSE.Lesson16;

import JavaSE.Lesson16.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestInsert {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st =null;
        ResultSet rs =null;

        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            String sql = "INSERT INTO account(id,`name`,`money`)\n" +
                    "VALUES(3,'CC','20000.00')";
            int i = st.executeUpdate(sql);
            if (i>0){
                System.out.println("插入成功！");
            }

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
           JdbcUtils.release(conn,st,rs);
        }
    }
}

3、编写数据库的增，删，改，查 主程序

3.1 删除

public class JdbcDelete {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st =null;
        ResultSet rs =null;

        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            String sql = "DELETE FROM account WHERE id =3";
            int i = st.executeUpdate(sql);
            if (i>0){
                System.out.println("删除成功！");
            }

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }

}

3.2 插入

public class TestInsert {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st =null;
        ResultSet rs =null;

        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            String sql = "INSERT INTO account(id,`name`,`money`)\n" +
                    "VALUES(3,'CC','20000.00')";
            int i = st.executeUpdate(sql);
            if (i>0){
                System.out.println("插入成功！");
            }

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
           JdbcUtils.release(conn,st,rs);
        }
    }
}

3.3 更改 更新

public class JdbcUpdate {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st =null;
        ResultSet rs =null;

        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            String sql = "UPDATE account SET `name`='AAAA',`money`='50000.00' WHERE id=1";
            int i = st.executeUpdate(sql);
            if (i>0){
                System.out.println("更新成功！");
            }

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

3.4 查询 （executeQuery）

public class JdbcSelect {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();

            //sql
            String sql = "SELECT * from account where id =1";
            rs = st.executeQuery(sql);
            while (rs.next()){
                System.out.println(rs.getString("name"));;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}