用sql server语句做一个外卖管理系统

好的，以下是一个简单的外卖管理系统的SQL Server语句：

1. 创建用户表

CREATE TABLE [dbo].[User](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [Username] [nvarchar](50) NOT NULL,
    [Password] [nvarchar](50) NOT NULL,
    [Nickname] [nvarchar](50) NULL,
    [Phone] [nvarchar](20) NOT NULL,
    [Address] [nvarchar](100) NOT NULL,
    CONSTRAINT [PK_User] PRIMARY KEY CLUSTERED 
    (
        [ID] ASC
    )
);

2. 创建商家表

CREATE TABLE [dbo].[Merchant](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [MerchantName] [nvarchar](50) NOT NULL,
    [Phone] [nvarchar](20) NOT NULL,
    [Address] [nvarchar](100) NOT NULL,
    CONSTRAINT [PK_Merchant] PRIMARY KEY CLUSTERED 
    (
        [ID] ASC
    )
);

3. 创建菜品表

CREATE TABLE [dbo].[Dish](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [DishName] [nvarchar](50) NOT NULL,
    [Description] [nvarchar](200) NULL,
    [Price] [decimal](18, 2) NOT NULL,
    [MerchantID] [int] NOT NULL,
    CONSTRAINT [PK_Dish] PRIMARY KEY CLUSTERED 
    (
        [ID] ASC
    ),
    CONSTRAINT [FK_Dish_Merchant] FOREIGN KEY([MerchantID])
    REFERENCES [dbo].[Merchant] ([ID])
);

4. 创建订单表

CREATE TABLE [dbo].[Order](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [UserID] [int] NOT NULL,
    [MerchantID] [int] NOT NULL,
    [DishIDs] [nvarchar](max) NOT NULL,
    [Address] [nvarchar](100) NOT NULL,
    [Amount] [decimal](18, 2) NOT NULL,
    [Status] [nvarchar](20) NOT NULL,
    CONSTRAINT [PK_Order] PRIMARY KEY CLUSTERED 
    (
        [ID] ASC
    ),
    CONSTRAINT [FK_Order_User] FOREIGN KEY([UserID])
    REFERENCES [dbo].[User] ([ID]),
    CONSTRAINT [FK_Order_Merchant] FOREIGN KEY([MerchantID])
    REFERENCES [dbo].[Merchant] ([ID])
);

以上是一个简单的外卖管理系统的SQL Server语句，可以实现用户注册、登录、下单、商家接单、配送等操作。当然，实际开发中还需要考虑数据的安全性、性能优化等方面。