JDBC增删改查(工具类)

剖析JDBC增删改查

工具类 用于1.加载数据库驱动，2.创建数据库连接

package JDBC_0921;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class mysqlUtil {

	private static final String Driver = "com.mysql.cj.jdbc.Driver";
	private static final String URL = "jdbc:mysql://127.0.0.1:3306/tt";
	private static final String UNAME = "root";
	private static final String PASSWD = "123456";
	static {
		try {
			Class.forName(Driver);
			System.out.println("1.数据库驱动加载成功");
		} catch (Exception e) {
			System.out.println("加载数据库驱动失败");
		}
	}

	public static final Connection getconnection() throws SQLException {
		Connection conn = DriverManager.getConnection(URL, UNAME, PASSWD);
//		conn.setAutoCommit(false);
		System.out.println("2.创建数据库连接");
		return conn;
	}

}

增加 insert

package JDBC_0921;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class InsertUtil {

	public static void InsertMethod(int id, String name, String email) throws SQLException {
		Connection conn = mysqlUtil.getconnection();
		PreparedStatement ps = null;
		String sql = "insert into student(id,name,email) values(?,?,?)";
		// 3.创建sql语句对象
		try {
			ps = conn.prepareStatement(sql);
			System.out.println("3.创建sql语句对象");
			ps.setInt(1, id);
			ps.setString(2, name);
			ps.setString(3, email);
			// 4.执行sql语句
			ps.executeUpdate();
			System.out.println("4.执行sql语句");
			System.out.println("插入成功");

		} catch (Exception e) {
			e.printStackTrace();
			System.out.println("插入异常");
		} finally {
			ps.close();
			conn.close();
			System.out.println("数据库连接关闭");
		}
	}

	public static void main(String[] args) throws SQLException {
		InsertMethod(1028, "java", "java.com");
	}
}

删除 delete

package JDBC_0921;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class DeleteUtil {
	public static void DeleteMethod(int id) throws SQLException {
		Connection conn = mysqlUtil.getconnection();
		PreparedStatement ps = null;
		String sql = "delete from student where id = ?";
		try {
			ps = conn.prepareStatement(sql);
			System.out.println("3.创建数据库对象");
			ps.setInt(1, id);
			ps.executeUpdate();
			System.out.println("4.执行数据库语句");
		} catch (Exception e) {
			e.printStackTrace();
			System.out.println("输出失败");
		} finally {
			ps.close();
			conn.close();
			System.out.println("5.关闭数据库连接");
		}
	}

	public static void main(String[] args) throws SQLException {
		DeleteMethod(24);
	}
}

修改 update

package JDBC_0921;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class UpdateUtil {

	public static void UpdateMethod(int id) throws SQLException {
		Connection conn = mysqlUtil.getconnection();
		PreparedStatement ps = null;
		String sql = "update student set email = 'sql' where id = ?";
		// 3.创建sql语句对象

		try {
			ps = conn.prepareStatement(sql);
			ps.setInt(1, id);
			System.out.println("3.创建sql语句对象");
			ps.executeUpdate();
			System.out.println("4.执行sql语句");

		} catch (Exception e) {
			e.printStackTrace();
			System.out.println("update异常");
		} finally {
			ps.close();
			conn.close();
			System.out.println("5.关闭数据库连接");
		}
	}

	public static void main(String[] args) throws SQLException {
		UpdateMethod(6);
	}

}

查询 select

package JDBC_0921;

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

public class SelectUtil {

	public static void SelectMethod(int select_id, String select_name) throws SQLException {
		Connection conn = mysqlUtil.getconnection();
		ResultSet rs = null;
		PreparedStatement ps = null;
		String sql = "select * from student where id = ? or name = ?";
		// 3.创建sql语句对象
		System.out.println("3.创建sql语句对象");
		try {
			ps = conn.prepareStatement(sql);
			ps.setInt(1, select_id);
			ps.setString(2, select_name);
			// 4.执行sql语句
			rs = ps.executeQuery();
			System.out.println("4.执行sql语句");
			while (rs.next()) {
				int id = rs.getInt("id");
				String name = rs.getString("name");
				String email = rs.getString("email");
//				if (name.equals("张三")) {
//					System.out.println("登录成功");
//					break;
//				}
				System.out.println("id：" + id + "\t\t" + "name:" + name + "\t\t" + "email:" + email);
			}
		} catch (Exception e) {
			System.out.println("查询异常");
		} finally {
			// 5.数据库连接关闭
			rs.close();
			ps.close();
			conn.close();
			System.out.println("5.数据库连接关闭");
		}

	}

	public static void main(String[] args) throws SQLException {
		SelectMethod(6, "apple");
	}

}