第一个JDBC代码

一、方法步骤：

1.加载驱动

 Class.forName("com.mysql.jdbc.Driver");//固定写法，加载驱动

2.用户信息和url

        String ur1="jdbc:mysql://localhost:3306/myemployees?useUnicode=true&characterEncoding=utf8&useSSL=true";//这一步就已经连上数据指定的表
                    //?表示连接参数
        //useUnicode（支持中文编码）=true&characterEncoding（中文字符编码）=utf8&useSSL(使用安全连接)=true
        String username="root";
        String passwrod="root";

3.连接成功，数据库对象

   Connection connection= DriverManager.getConnection(ur1,username,passwrod);

4.执行sql的对象。

Statement statement=connection.createStatement();

5.执行sql的对象 去执行sql。可能有返回值。

 String sql1="SELECT*FROM `jobs`;";
        ResultSet resultSet= statement.executeQuery(sql1);
       //返回的结果集，结果集中封装了我们全部的查询出来的结果
        while (resultSet.next()){
    
    
            System.out.println("job_id="+resultSet.getObject("job_id"));
            System.out.println("job_title="+resultSet.getObject("job_title"));
            System.out.println("min_salary="+resultSet.getObject("min_salary"));
            System.out.println("max_salary="+resultSet.getObject("max_salary"));
            System.out.println("================================");
        }

6.释放连接

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

二、运行结果对比：

1、在IDEA上

C:\Users\蜗牛\.jdks\corretto-11.0.10\bin\java.exe "-javaagent:D:\IDEA\IntelliJ IDEA 2020.2.3\lib\idea_rt.jar=7913:D:\IDEA\IntelliJ IDEA 2020.2.3\bin" -Dfile.encoding=UTF-8 -classpath C:\Users\蜗牛\Desktop\扬州学习\IdeaProjects\12\out\production\jdbc;C:\Users\蜗牛\IdeaProjects\jdbc\libs\mysql-connector-java-5.1.37-bin.jar jdbc.jdbc2
job_id=AC_ACCOUNT
job_title=Public Accountant
min_salary=4200
max_salary=9000
================================
job_id=AC_MGR
job_title=Accounting Manager
min_salary=8200
max_salary=16000
================================
job_id=AD_ASST
job_title=Administration Assistant
min_salary=3000
max_salary=6000
================================
job_id=AD_PRES
job_title=President
min_salary=20000
max_salary=40000
================================
job_id=AD_VP
job_title=Administration Vice President
min_salary=15000
max_salary=30000
================================
job_id=FI_ACCOUNT
job_title=Accountant
min_salary=4200
max_salary=9000
================================
job_id=FI_MGR
job_title=Finance Manager
min_salary=8200
max_salary=16000
================================
job_id=HR_REP
job_title=Human Resources Representative
min_salary=4000
max_salary=9000
================================
job_id=IT_PROG
job_title=Programmer
min_salary=4000
max_salary=10000
================================
job_id=MK_MAN
job_title=Marketing Manager
min_salary=9000
max_salary=15000
================================
job_id=MK_REP
job_title=Marketing Representative
min_salary=4000
max_salary=9000
================================
job_id=PR_REP
job_title=Public Relations Representative
min_salary=4500
max_salary=10500
================================
job_id=PU_CLERK
job_title=Purchasing Clerk
min_salary=2500
max_salary=5500
================================
job_id=PU_MAN
job_title=Purchasing Manager
min_salary=8000
max_salary=15000
================================
job_id=SA_MAN
job_title=Sales Manager
min_salary=10000
max_salary=20000
================================
job_id=SA_REP
job_title=Sales Representative
min_salary=6000
max_salary=12000
================================
job_id=SH_CLERK
job_title=Shipping Clerk
min_salary=2500
max_salary=5500
================================
job_id=ST_CLERK
job_title=Stock Clerk
min_salary=2000
max_salary=5000
================================
job_id=ST_MAN
job_title=Stock Manager
min_salary=5500
max_salary=8500
================================

Process finished with exit code 0

2、在SQLyog上做查询语句

SELECT*FROM`jobs`;

结果：

三、总结：

1.加载驱动
2.用户信息和url
3.连接成功，数据库对象
4.执行sql的对象。
5.执行sql的对象 去执行sql。可能有返回值。
6.释放连接。