Use SQL Server Management Studio In Object Explorer, right-click the table to which you want to add a unique constraint, and selectDesign. InTable Designer, select the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold...
You can create a unique constraint in SQL Server by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that don't participate in a primary key. Creating a unique constraint automatically creates a corresponding unique index....
syntaxsql 複製 CREATE TABLE { database_name.schema_name.table_name | schema_name.table_name | table_name } ( { <column_definition> | [ ] [ ,... n ] | [ ] [ ,... n ] } [ PERIOD FOR SYSTEM_TIME ( system_start_time_column_name , system_end_time_column_name ) ] ) ...
alter table orders add constraint fk_employee_creator_order foreign key (eid) references employee(employeeid) 使用表自引用 表内至少要有一行数据才可以这么做 alter table employee add constraint fk_employee_has_manager foreign key (managerid) references employee(employeeid) 创建表的时候做表自引用 就可...
To define a column in a table To define a CHECK constraint on a column To replace a stored procedure Use an inline function as a filter predicate for a security policy The integration of .NET Framework CLR into SQL Server is discussed in this article. CLR integration doesn't apply to Azur...
syntaxsql CREATETYPE[schema_name. ]type_nameASTABLE( {<column_definition>[ , ...n ] } | [] [ , ...n ] | [] [ , ...n ] ) [WITH([ , ...n ] ) ] [ ; ]<column_definition>::=column_name<data_type>[COLLATEcollation_name] [NULL|NOTNULL] [IDENTITY[ (1,1) ] ] [<col...
Learn how to can create a check constraint in a table to specify the data values that are acceptable in one or more columns in the SQL Server Database Engine.
syntaxsql CREATETYPE[schema_name. ]type_nameASTABLE( {<column_definition>[ , ...n ] } | [] [ , ...n ] | [] [ , ...n ] ) [WITH([ , ...n ] ) ] [ ; ]<column_definition>::=column_name<data_type>[COLLATEcollation_name] [NULL|NOTNULL] [IDENTITY[ (1,1) ] ] [<col...
但是,在启用 clr 启用选项之前,无法在 SQL Server 中执行这些引用。 若要启用此选项,请使用 sp_configure。 此选项在包含的数据库中不可用。<> table_type_definition ( { <column_definition><column_constraint | <> computed_column_definition } [ ] [ , ...n ]定义Transact-SQL 函数的表数据类型。
SQL SELECT INTO 语句可用于创建表的备份复件。 SELECT INTO 语句 SELECT INTO 语句从一个表中选取数据,然后把数据插入另一个表中。 SELECT INTO 语句常用于创建表的备份复件或者用于对记录进行存档。 SQL SELECT INTO 语法 您可以把所有的列插入新表: ...