为了解决上述问题,我们可以使用SQL Server数据库的Key来定义唯一约束和关系。在SQL Server中,我们可以使用主键(Primary Key)和外键(Foreign Key)来实现。 定义商品表 首先,我们创建一个商品表,包括商品编号(Product ID)、商品名称(Product Name)和商品描述(Product Description)等字段。 CREATETABLEProducts(ProductIDINT...
Applies to: SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed InstanceYou can define a primary key in SQL Server by using SQL Server Management Studio or Transact-SQL. Creating a primary key automatically creates a corresponding unique clustered index, or a nonclustered ...
{ Server svr = new Server(); Database db = new Database(svr, "TESTDB"); db.Create(); // PK Table Table tab1 = new Table(db, "Table1"); // Define Columns and add them to the table Column col1 = new Column(tab1, "Col1", DataType....
SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance You can define a primary key in the SQL Server Database Engine by using SQL Server Management Studio or Transact-SQL. Creating a primary key automatically creates a corresponding unique clustered index. However, you...
SQL Server 基本数据类型: 1.1简介 1.1.1SQL分类 <!--[if !supportLists]-->l <!--[endif]-->DDL(Data Define Language):数据定义语言: <!--[if !supportLists]-->n <!--[endif]-->create [table,index,view,procedure] <!--[if !supportLists]-->n <!--[endif]-->drop [table,index,view...
Server:Msg 8111, Level 16, State 2, Line 1 Cannot define PRIMARY KEY constraint on nullable column in table 'T2'. Server:Msg 1750, Level 16, State 1, Line 1 Could not create constraint.See previous errors. 因为主键约束,所以 SQL Server 需要您保证计算的结果不为 NULL。计算列中的计算可以上...
Here's how you can define aPrimary Key: 1. While creating a table (Single column as Primary Key): CREATE TABLE Employees ( ID int NOT NULL PRIMARY KEY, FirstName varchar(255) NOT NULL, LastName varchar(255) NOT NULL ); In this example, theIDfield is the primary key of the "Employ...
{ Server svr = new Server(); Database db = new Database(svr, "TESTDB"); db.Create(); // PK Table Table tab1 = new Table(db, "Table1"); // Define Columns and add them to the table Column col1 = new Column(tab1, "Col1", DataType.Int); col1.Nullable = false; tab1....
By far the simplest and most common technique for adding a primary key in Postgres is by using the SERIAL or BIGSERIAL data types when CREATING a new table. As indicated in the official documentation, SERIAL is not a true data type, but is simply shorthand notation that tells Postgres to ...
SQL_SERVER_NAME 1.0 具有实际数据源特定服务器名称的字符串;在 SQLConnect、SQLDriverConnect 和SQLBrowseConnect 期间使用数据源名称时非常有用。 SQL_SPECIAL_CHARACTERS 2.0 一个字符串,其中包含所有特殊字符(即,除通过 z、A 到 Z、0 到 9 和下划线)的所有字符(可用于数据源的标识符名称(如表名、列名或索引名...