eclipse连接数据库 进行增删改查操作

package test0813;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class Test02 {
    
    

	public void doSelect(int Id) {
    
    // 根据主键查询
		try {
    
    
			Class.forName("com.mysql.jdbc.Driver");
			Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/emp?characterEncoding=utf-8",
					"root", "root");
			PreparedStatement pst = con.prepareStatement("select * from dept where Id=?");
			pst.setInt(1, Id);// 给第一个问号传了值
			ResultSet rs = pst.executeQuery();

			if (rs.next()) {
    
    // 如果有下一行才输出,不会报空指针异常
				System.out.println(rs.getInt("Id") + "\t" + rs.getString("dname") + "\t" + rs.getString("loc"));
			}
			rs.close();
			pst.close();
			con.close();
		} catch (Exception e) {
    
    
			e.printStackTrace();
		}
	}

	public void doInsert(int Id, String dname, String loc) {
    
    // 插入
		try {
    
    
			Class.forName("com.mysql.jdbc.Driver");
			Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/emp?characterEncoding=utf-8",
					"root", "root");
			PreparedStatement pst = con.prepareStatement("insert into dept values(?,?,?)");
			pst.setInt(1, Id);// 给第一个问号传了值
			pst.setString(2, dname);
			pst.setString(3, loc);
			int result = pst.executeUpdate();// 增删改都用update

			if (result > 0) {
    
    
				System.out.println("ok");
			} else {
    
    
				System.out.println("error");
			}

			pst.close();
			con.close();
		} catch (Exception e) {
    
    
			e.printStackTrace();
		}
	}

	public void doUpdate(int Id, String dname, String loc) {
    
    // 更新
		try {
    
    
			Class.forName("com.mysql.jdbc.Driver");
			Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/emp?characterEncoding=utf-8",
					"root", "root");
			PreparedStatement pst = con.prepareStatement("update dept set dname=?,loc=? where Id=?");
			pst.setString(1, dname);
			pst.setString(2, loc);
			pst.setInt(3, Id);
			int result = pst.executeUpdate();// 增删改都用update

			if (result > 0) {
    
    
				System.out.println("ok");
			} else {
    
    
				System.out.println("error");
			}

			pst.close();
			con.close();
		} catch (Exception e) {
    
    
			e.printStackTrace();
		}
	}

	public void doDelete(int Id) {
    
    // 删除,一般按主键
		try {
    
    
			Class.forName("com.mysql.jdbc.Driver");
			Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/emp?characterEncoding=utf-8",
					"root", "root");
			PreparedStatement pst = con.prepareStatement("delete from dept where Id=?");
			pst.setInt(1, Id);
			int result = pst.executeUpdate();// 增删改都用update

			if (result > 0) {
    
    
				System.out.println("ok");
			} else {
    
    
				System.out.println("error");
			}

			pst.close();
			con.close();
		} catch (Exception e) {
    
    
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
    
    
		// new Test02().doSelect(10);
		// new Test02().doInsert(50, "技术部", "沈阳市");
		// new Test02().doUpdate(50, "技术1部", "大城市");
		new Test02().doDelete(50);
	}

}