JavaJDBC【三、增删改查】

获取数据库连接后，可进行增删改查操作

• 语句生成：
  
  Statement s = con.createStatement(sql); //生成语句
  
  PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql); //预准备，可以填充参数
  
  ps.setXXX(n,value); //可以通过set来填充参数值，位置，值

• 参数查询：
  
  s.executeUpdate(); //执行非查询操作，增删改
  
  s.executeQuery(); //执行查询

Demo:

public class JDBCDAO {

public static int addJDBC(JDBCModel m) throws SQLException {
	Connection c = DBUtil.GetConnection();

	// current_time() mysql内置函数，当前时间
	String sql = "insert jdbc (id,name,createtime) "
			+ "values(?,?,current_time())";
	PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql);
	ps.setLong(1, 0);// 主键自增
	ps.setString(2, m.name);

	int re = 0;
	try {
		// 此处若使用execute，会返回false，但插入成功
		// false代表第一个执行结果的返回值不是resultset
		re = ps.executeUpdate();
		System.out.println(re);
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	return re;
}

public static int deleteJDBC(int i) throws SQLException {
	Connection c = DBUtil.GetConnection();

	String sql = "delete from jdbc where id=?";
	PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql);
	ps.setLong(1, i);

	int re = 0;
	try {
		// 此处若使用execute，会返回false，但插入成功
		// false代表第一个执行结果的返回值不是resultset
		re = ps.executeUpdate();
		System.out.println(re);
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	return re;
}

public static int updateJDBC(JDBCModel m) throws SQLException {
	Connection c = DBUtil.GetConnection();

	String sql = "update jdbc set name=? where id=?";
	PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql);
	ps.setString(1, m.name);
	ps.setLong(2, m.id);

	int re = 0;
	try {
		re = ps.executeUpdate();
		System.out.println(re);
	} catch (SQLException e) {
		e.printStackTrace();
	}
	return re;
}

public static List<JDBCModel> queryJDBC() throws SQLException {
	List<JDBCModel> ml = new ArrayList<JDBCModel>();
	Connection c = DBUtil.GetConnection();

	String sql = "select * from jdbc  ";
	PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql);

	ResultSet re = null;
	try {
		re = ps.executeQuery();
	} catch (SQLException e) {
		e.printStackTrace();
	}
	if (re != null) {
		while (re.next()) {
			JDBCModel m = new JDBCModel();
			m.setId(re.getInt("id"));
			m.setName(re.getString("name"));
			m.setCreatetime(re.getDate("createtime"));
			ml.add(m);
		}
	}
	return ml;
}
}