五月二十五日jdbc基础知识点

Jdbc连接数据库
1.建立与数据库的连接
1.1导入jdbc包
1.2加载JDBC驱动
java.lang.Class.forName(JDBCDriverClass);
Class.forName(driver);
MySQL的加载驱动
Class.forName(com.mysql.jdbc.Driver);
1.3获取数据库连接对象
Connection conn = DriverManager.getConnection(url,user,password);
2执行SQL语句
步骤一：创建Statement对象
步骤二：调用Statement对象相应方法将Sql语句发送到所连接数据库
2.1创建执行对象
Statement stmt = conn.createStatement();
2.2执行查询语句：
public ResultSet executeQuery(String selectSql)
ResultSet rs = stmt.executeQuery(selectSql);
2.3 执行增删改语句：
public ResultSet executeUpdate(String updateSql);
Result rs = stmt.executeUpdate(updateSql);
3.处理返回结果
while(rs.next()){
String no = rs.getString("sNo");
String name = rs.getString("sName");
String sex = rs.getString("sex");
Int age = rs.getInt("age");
String dept = rs.getString("dept");
String address = rs.getString("address");
System.out.println(no+"\t"+name+"\t"+sex+"\t"+age+"\t"+dept+"\t"+address));
};
4.关闭创建的各种对象
步骤1：关闭结果集对象rs
步骤2：关闭执行对象stmt
步骤3：关闭数据库连接对象conn
try{
if(rs!=null) rs.close();
if(stmt!=null) stmt.close();
if(conn!=null) conn.close();}
catch(Exeption e){e.printStackTrace();}

public class app17_15 {

    private static String driver = "com.mysql.jdbc.Driver";

    private static String url = "jdbc:mysql://localhost:3306/ku";

    private static String user = "root";

    private static String password = "root";

    public static void main(String[] args) {

        String sql = "SELECT sNo,sName,sex,age,dept,address FROM student WHERE dept = '计算机'";

        try(

                //创建数据库连接

                Connection conn= DriverManager.getConnection(url,user,password);

                //执行SQL语句

                Statement stmt = conn.createStatement();

                //处理返回结果

                ResultSet rs = stmt.executeQuery(sql);

                ){

            Class.forName(driver);//加载MySQL的驱动

            while(rs.next()){

                String no = rs.getString("sNo");

                String name = rs.getString("sName");

                String sex = rs.getString("sex");

                int age = rs.getInt("age");

                String dept = rs.getString("dept");

                String address = rs.getString("address");

                System.out.println(no+"\t"+name+"\t"+sex+"\t"+age+"\t"+dept+"\t"+address);

            }

        }

                catch (Exception e){

            e.printStackTrace();

                }

    }

}

5.jdbc中三种SQL对表查询方式
第一种：Statement接口执行不带参数的静态SQL语句查询
静态SQL语句指执行executeQuery()以及executeUpdate()方法时，
SQL语句没有参数
第二种：PreparedStatement接口执行动态SQL语句查询
第三种：CallableStatement接口执行存储过程调用

public class app17_16 {

    private static String driver = "com.mysql.jdbc.Driver";

    private static String url = "jdbc:mysql://localhost:3306/ku";

    private static String user = "root";

    private static String password = "root";

    public static void main(String[] args) {

        String selectSql = "SELECT * FROM student WHERE dept = '计算机'";

        String insertSql = "INSERT INTO student(sNo,sName,sex,age,dept,address) VALUES('9','刘六','女',22,'外语','湖南')";

        String updateSql = "UPDATE student SET dept ='金融' WHERE sNo = '7'";

        String deleteSql = "DELETE FROM student WHERE sNo = '3'";

        try(

                Connection conn  = DriverManager.getConnection(url,user,password);

                Statement stmt = conn.createStatement();

                ResultSet rs = stmt.executeQuery(selectSql);

                ){

            Class.forName(driver);

            while(rs.next()) {

                String no = rs.getString("sNo");

                String name = rs.getString("sName");

                String sex = rs.getString("sex");

                int age = rs.getInt("age");

                String dept = rs.getString("dept");

                String address = rs.getString("address");

                System.out.println(no + "\t" + name + "\t" + sex + "\t" + age + "\t" + dept + "\t" + address);

            }

            {

                int count = stmt.executeUpdate(insertSql);

                System.out.println("添加了"+count+"记录到student表");

                count = stmt.executeUpdate(updateSql);

                System.out.println("修改了"+count+"记录到student表");

                count = stmt.executeUpdate(deleteSql);

                System.out.println("删除了"+count+"记录到student表");

            }

        }

                catch (Exception e){

            e.printStackTrace();

                }

    }

}

总结：熟悉了一遍数据库与idea的连接

创建数据库连接对象

创建SQL执行对象

处理返回结果集

关闭对象

令我耗时的是程序出来咯，但由于没有导入jar包，导致出错

五月二十五日jdbc基础知识点的相关教程结束。