sql数据库架构中建表

-- 示例：规范化设计
CREATE TABLE Users (
    UserID INT PRIMARY KEY,
    UserName VARCHAR(50),
    Email VARCHAR(100)
);

CREATE TABLE Orders (
    OrderID INT PRIMARY KEY,
    UserID INT,
    OrderDate DATETIME,
    FOREIGN KEY (UserID) REFERENCES Users(UserID)
);

-- 示例：合理选择数据类型
CREATE TABLE Products (
    ProductID INT PRIMARY KEY,
    ProductName VARCHAR(100),
    Price DECIMAL(10, 2), -- 精确到小数点后两位
    Stock INT
);

-- 示例：检查约束条件
CREATE TABLE Employees (
    EmployeeID INT PRIMARY KEY,
    DepartmentID INT,
    FOREIGN KEY (DepartmentID) REFERENCES Departments(DepartmentID)
);

CREATE TABLE Departments (
    DepartmentID INT PRIMARY KEY,
    DepartmentName VARCHAR(50)
);

-- 插入数据时确保DepartmentID存在
INSERT INTO Employees (EmployeeID, DepartmentID) VALUES (1, 1);