column1, column2, ... column_n The columns that make up the unique constraint. Example Let's look at an example of how to add a unique constraint to an existing table in SQL Server using the ALTER TABLE statement. ALTER TABLE employees ADD CONSTRAINT employees_unique UNIQUE (employee_numbe...
SQL Server、Azure SQL Database、Azure SQL 受控執行個體的語法syntaxsql 複製 CREATE [ UNIQUE ] [ CLUSTERED | NONCLUSTERED ] INDEX index_name ON <object> ( column [ ASC | DESC ] [ ,...n ] ) [ INCLUDE ( column_name [ ,...n ] ) ] [ WHERE <filter_predicate> ] [ WITH ( <...
Server. $tb.Create() #Create a unique, clustered, primary key index on the integer column. This is required for an XML index. #Define an Index object variable by providing the parent table and index name in the constructor. $cp = New-Object -TypeName Microsoft.SqlServer.Man...
FORCESEEK [ ( <index_value> ( <index_column_name> [ , ...n ] ) ) ]指定查詢最佳化工具只使用索引搜尋作業做為資料表或檢視表資料的存取路徑。注意 從SQL Server 2008 R2 (10.50.x) Service Pack 1 開始,您也可以指定索引參數。 如此一來,查詢最佳化工具只會考慮至少使用指定索引資料行之指定索引的...
理解SQL Server约束的基本知识。 学会使用SQL语句查询约束名称。 提供相关代码示例以帮助用户更好地理解。 约束的基础知识 约束可以分为几种主要类型,包括: 主键约束(Primary Key) 外键约束(Foreign Key) 唯一性约束(Unique) 检查约束(Check) 默认约束(Default) ...
Set preferred DNS server address The preferred DNS server addressshould not be updateddirectly within a VM, it should be edited from theAzure portal, or Powershell, or Azure CLI. The steps below are to make the change inside of the Azure portal: ...
'VARCHAR' is not a recognized built-in function name. 'WHEN MATCHED' cannot appear more than once in a 'UPDATE' clause of a MERGE statement. "EXECUTE AT" with Dynamic Linked Server Name "explicit value must be specified for identity column in table" error in SQL 2000 "FROM clause have ...
FOREIGN KEY 所引用的列必须是有PRIMARY KEY 或UNIQUE约束的列。 举例:创建一个学生表,包含学号、学生姓名、性别、年龄、国籍、班名、出生地 列,SQL命令如下: create table Student /*创建 学生表 */ ( /*约束 约束名 设置主键*/ sno varchar(12) constraint s_prim primary key, ...
_DATA_SOURCE='data_source_name'] [ ,FIRSTROW=first_row] [ ,LASTROW=last_row] [ ,MAXERRORS=maximum_errors] [ ,ERRORFILE='file_name'] [ ,ERRORFILE_DATA_SOURCE='data_source_name'] [ ,ROWS_PER_BATCH=rows_per_batch] [ ,ORDER( { column [ASC|DESC] } [ , ...n ] ) [UNIQUE] ...
The preferred DNS server address should not be updated directly within a VM, it should be edited from the Azure portal, or PowerShell, or Azure CLI. The steps below are to make the change inside of the Azure portal:Sign-in to the Azure portal. In the search box at the top of the ...