sql,CREATE DATABASE 订单管理;,USE 订单管理;,
``ALTER TABLE
语句来为现有表添加新列。要为名为 products
的表添加一个名为 new_column
的新列,数据类型为 VARCHAR(255)
,可以使用以下 SQL 命令:,,``sql,ALTER TABLE products ADD COLUMN new_column VARCHAR(255);,
``sql,CREATE TABLE Products (, ProductID INT PRIMARY KEY,, ProductName VARCHAR(255),, Category VARCHAR(100),, Price DECIMAL(10, 2),, Stock INT,);,,CREATE TABLE Users (, UserID INT PRIMARY KEY,, Username VARCHAR(255),, Password VARCHAR(255),, Email VARCHAR(255),);,,CREATE TABLE Orders (, OrderID INT PRIMARY KEY,, UserID INT,, OrderDate DATETIME,, FOREIGN KEY (UserID) REFERENCES Users(UserID),);,,CREATE TABLE OrderDetails (, OrderDetailID INT PRIMARY KEY,, OrderID INT,, ProductID INT,, Quantity INT,, FOREIGN KEY (OrderID) REFERENCES Orders(OrderID),, FOREIGN KEY (ProductID) REFERENCES Products(ProductID),);,
``Powered By Z-BlogPHP 1.7.3