mysql數據庫增刪改查

package DButls;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.List;

public class JDBCTest {
    public <T> List<T> query(Class<T> clazz, String sql){
        return null;
    }
    /*
    resultset 是封裝JDBC的結果集
    1.調用 statement 的對象executeQuery 就能夠獲得結果集
    ResultSet 返回的實際上就是一張數據表. 有一個指針指向數據表的第同樣的前面.
    * 能夠調用 next() 方法檢測下一行是否有效. 如有效該方法返回 true, 且指針下移. 至關於
    * Iterator 對象的 hasNext() 和 next() 方法的結合體
    * 3. 當指針對位到一行時, 能夠經過調用 getXxx(index) 或 getXxx(columnName)
    * 獲取每一列的值. 例如: getInt(1), getString("name")
    * 4. ResultSet 固然也須要進行關閉.
     */

    public void testResultset(){
        //獲取ID是4的student
        Connection connection = null;//鏈接
        Statement statement =null;
        ResultSet resultSet = null;
        try{
            //1 獲取數據庫鏈接
            connection = JDBCTools.getConnection();
            System.out.println(connection);
            //2.獲取statement
            statement = connection.createStatement();
            System.out.println(statement);
            //3準備mysql
            String sql = "SELECT * FROM STUDENTS";
            resultSet = statement.executeQuery(sql);
            System.out.println(resultSet);
            //處理返回的結果集
            while (resultSet.next()){
                int id = resultSet.getInt(1);
                String name = resultSet.getString("name");
                String age = resultSet.getString("age");
                System.out.print("id = "+id);
                System.out.print("name = "+name);
                System.out.println("age = "+age);


            }


        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JDBCTools.release(resultSet, statement, connection);
        }
    }


    /*
    執行插入  修改   刪除
     */
        public void TestInsert()throws  Exception{
            Connection connection = null;
            Statement statement = null;
            try{
                String sql = "INSERT INTO students(NAME,age)VALUES(\"bbbb\",\"57\")";
                connection = JDBCTools.getConnection();
                statement = connection.createStatement();
                statement.executeUpdate(sql);
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                JDBCTools.release(statement, connection);
            }
        }

        //刪除數據庫
        public void  TesTdelect(){
            Connection connection = null;
            Statement statement = null;
            try{
                String sql="DELETE FROM students WHERE id > 3";
                connection = JDBCTools.getConnection();
                statement = connection.createStatement();
                statement.executeUpdate(sql);
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                JDBCTools.release(statement, connection);
            }
        }
        //嘗試修改數據
        public void TestUpdate() throws  Exception{
            Connection connection = null;
            Statement statement = null;
            try {
                String sql = "UPDATE students SET age = '200' where name  = 'zhangsan' ";
                connection = JDBCTools.getConnection();
                statement = connection.createStatement();
                statement.executeUpdate(sql);
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                JDBCTools.release(statement, connection);
            }
        }

}