數據查詢:
/**
* 登錄/查詢
*
* @param user
* @param password
* @throws ClassNotFoundException
*/
public static void login(String user, String password) {
Connection connection = null;
PreparedStatement statement = null;
ResultSet resultSet = null;
try {
// 1、加載驅動//6.0以下數據庫需要加載
// Class.forName("com.mysql.jdbc.Driver");
// 2、建立連接
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/user?serverTimezone=GMT&useSSL=false",
"root", "root");
// 3、操作數據庫
// 1)預編譯SQL格式
String sql = "SELECT * FROM student WHERE name=? AND password=?";
statement = connection.prepareStatement(sql);
// 2)給SQL中的佔位符設置值
statement.setString(1, user); // 給語句中的第一個問號設置值
statement.setString(2, password); // 給語句中的第二個問號設置值
// 3)執行查詢
resultSet = statement.executeQuery();
// 4)從resultset中獲取結果
if (resultSet.next()) {
System.out.println("登錄成功,當前登錄用戶:" + user + ",性別:" + resultSet.getString("sex"));
} else {
System.out.println("登錄失敗,用戶名或密碼錯誤!");
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
// 4、關閉連接
try {
if (resultSet != null) {
resultSet.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (statement != null) {
statement.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
數據新增:
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
// 連接數據庫
try {
connection = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/server?serverTimezone=GMT&useSSL=false", "root", "root");
// 新增數據的sql語句
String sql = "insert into user values(?,?,?,?) ";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, username);
preparedStatement.setString(2, password);
preparedStatement.setString(3, name);
preparedStatement.setInt(4, age);
preparedStatement.executeUpdate();
//關閉連接沒有寫
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
數據修改
// // 操作數據庫
// String sql = "UPDATE student SET sex=? WHERE name=?";
// PreparedStatement statement = connection.prepareStatement(sql);
// statement.setString(1, "男");
// statement.setString(2, "李四");
// statement.executeUpdate();
// System.out.println("修改成功!");
//
// // 關閉連接
// statement.close();
// connection.close();
數據刪除:
// PreparedStatement preparedStatement = connection.prepareStatement("DELETE FROM student WHERE id=2");
// preparedStatement.executeUpdate();
// System.out.println("刪除成功!");
//
// // 關閉連接
// preparedStatement.close();
// connection.close();