更新SQL外键值触发UPDATE错误，请求排查解决

尝试更新Reservations表中指定id_reservation的id_room字段值为idRoom变量内容时，UPDATE操作执行失败，已通过谷歌搜索未找到有效解决方案，需帮忙排查问题。

执行的C#及SQL代码 #

data = "UPDATE Reservations SET id_room = @idRoom FROM Reservations WHERE id_reservation = @idReservation";

using (SqlCommand cmd = new SqlCommand(data, con))
{
    cmd.Parameters.AddWithValue("@idRoom", idRoom);
    cmd.Parameters.AddWithValue("@idReservation", idReservationTxtBox.Text);
    cmd.ExecuteNonQuery();
}

关联表结构 #

Reservations表 #

CREATE TABLE [dbo].[Reservations] (
    [id_reservation]  INT          IDENTITY (1, 1) NOT NULL,
    [n_card]          VARCHAR (16) NOT NULL,
    [cardholder_name] TEXT         NOT NULL,
    [expiration_date] DATE         NOT NULL,
    [cvc]             VARCHAR (3)  NOT NULL,
    [id_room]         INT          NOT NULL,
    [reserva_price]   FLOAT (53)   NOT NULL,
    [check-in]        DATETIME     NOT NULL,
    [check-out]       DATETIME     NOT NULL,
    CONSTRAINT [PK_Reservas] PRIMARY KEY CLUSTERED ([id_reservation] ASC),
    CONSTRAINT [FK_Reservations_Rooms] FOREIGN KEY ([id_room]) REFERENCES [dbo].[Rooms] ([id_room])
);

Rooms表 #

CREATE TABLE [dbo].[Rooms] (
    [id_room]   INT  IDENTITY (1, 1) NOT NULL,
    [n_room]    INT  NOT NULL,
    [type_room] TEXT NOT NULL,
    [available] BIT  NOT NULL,
    CONSTRAINT [PK_Rooms] PRIMARY KEY CLUSTERED ([id_room] ASC)
);

补充材料 #

已提供以下截图：

• SQL错误信息截图
• Reservations和Rooms表的结构及数据截图
• idRoom变量定义截图

内容的提问来源于stack exchange，提问作者bagaco