JDBC的安裝與使用

JDBC的安裝

   首先在登錄MySQL的官網下載JDBC-MySQL數據庫驅動，或者去www.mysql.com/products/connector直接下載。

   因為jdbc包屬於第三方包，因此要自己導入，下面是導入的方法：

https://jingyan.baidu.com/article/3aed632e1a4ceb70108091f6.html

       導入之后就創建一個connect類來編寫代碼，來測試是否能與服務器連接。

　　

import java.sql.*;//導入sql包
public class connect {
    
    public static void main(String args[]) throws SQLException, ClassNotFoundException
    {    
        //數據庫連接
        Statement sql;//數據庫
        ResultSet rs;//數據
        Connection conn;//用於連接
        String url = "jdbc:mysql://localhost:3306/students?serverTimezone=UTC&useSSL=false";
        String username = "root";
        String password = "123456";//密碼自己修改
        //Class.forName("com.mysql.cj.jdbc.Driver");//加載JDBC-MySQL驅動
        conn =
DriverManager.getConnection(url,username,password);//連接完畢
try{
            Class.forName("com.mysql.cj.jdbc.Driver");//加載JDBC-MySQL驅動
            conn = DriverManager.getConnection(url,username,password);
            
            if(conn != null){
                System.out.println("數據庫連接成功!");
                
            }else{
                System.out.println("數據庫連接失敗！");
            }
        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }catch(SQLException e){
            e.printStackTrace();
        }
}
}
       

如果數據庫可以連接之后就可以來試一下數據庫的基本操作；

import java.sql.*;//導入sql包
public class connect {
    
    public static void main(String args[]) throws SQLException, ClassNotFoundException
    {    
        //數據庫連接
        Statement sql;//數據庫
        ResultSet rs;//數據
        Connection conn;//用於連接
        String url = "jdbc:mysql://localhost:3306/students?serverTimezone=UTC&useSSL=false";
        String username = "root";
        String password = "123456";//密碼
        //Class.forName("com.mysql.cj.jdbc.Driver");//加載JDBC-MySQL驅動
        conn = DriverManager.getConnection(url,username,password);//連接完畢
        
        //添加篩選條件
            String c1 = " year(birthday)<=2000 and month(birthday)>7";
            String c2 = " name Like '張_%' ";
            String c3 = " height >1.65";
            String sqlStr="select * from mess where" +c1+ " and "+c2+ " and "+c3+"order by birthday";
            try {
                sql = conn.createStatement();
                rs = sql.executeQuery(sqlStr);
                while(rs.next())
                {
                    String number=rs.getString(1);
                    String name=rs.getString(2);
                    Date date =rs.getDate(3);
                    float height=rs.getFloat(4);
                    System.out.printf("%s\t",number);
                    System.out.printf("%s\t",name);
                    System.out.printf("%s\t",date);
                    System.out.printf("%.2f\t",height);
                    System.out.printf("\n");
                }
                //conn.close();
            }
            catch(SQLException e)
            {
                System.out.println(e);
                
            }
        System.out.println("--------華麗的分割線---------");
        
        /*try{
            Class.forName("com.mysql.cj.jdbc.Driver");//加載JDBC-MySQL驅動
            conn = DriverManager.getConnection(url,username,password);
            
            if(conn != null){
                System.out.println("數據庫連接成功!");
                
            }else{
                System.out.println("數據庫連接失敗！");
            }
        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }catch(SQLException e){
            e.printStackTrace();
        }*/
    
    
    //順序查詢
    try {
        //conn = DriverManager.getConnection(url,username,password);
        sql = conn.createStatement();
        rs = sql.executeQuery("SELECT*FROM mess");
        while(rs.next()) {
            String number=rs.getString(1);
            String name=rs.getString(2);
            Date date =rs.getDate(3);
            float height=rs.getFloat(4);
            System.out.printf("%s\t",number);
            System.out.printf("%s\t",name);
            System.out.printf("%s\t",date);
            System.out.printf("%.2f\t",height);
            System.out.printf("\n");
            
        }
        conn.close();
    }
    catch(SQLException e)
    {
        System.out.println(e);
        
    }
    
    
}
}

可能會遇到的問題：

　　　　JDBC連接MYSQL數據庫失敗，Loading class `com.mysql.jdbc.Driver'. This is deprecated.

　　　　　　https://blog.csdn.net/weixin_42323802/article/details/82589743