SQL PRIMARY KEY,SQL FOREIGN KEY A primary key is defined as a column or a group of column that their value are always be unique. Normally, NULL value will never be allowed in this column to be part of this column’s records.EXAMPLE sql SQL SQL FOREIGN KEY 约束 SQL FOREIGN KEY 约束...
ALTER TABLE [dbo].[T_Student] WITH CHECK ADD CONSTRAINT [FK_T_STUDEN_REFERENCE_T_TEACHE] FOREIGN KEY([TeacherID]) REFERENCES [dbo].[T_Teacher] ([ID]) ON UPDATE CASCADE ON DELETE CASCADE GO ALTER TABLE [dbo].[T_Student] CHECK CONSTRAINT [FK_T_STUDEN_REFERENCE_T_TEACHE] GO 分类: 摘...
IdentityValueKeyOption IfStatement IgnoreDupKeyIndexOption IIfCall ImportanceParameterType IndexDefinition IndexExpressionOption IndexOption IndexOptionKind IndexStatement IndexStateOption IndexTableHint IndexType IndexTypeKind InlineDerivedTable InlineFunctionOption InlineResultSetDefinition InPredicate Insert...
SQL Server Agent是SQL Server中的一个Windows 服务,该服务用来运行制定的计划任务。计划任务其实是在SOL Server中定义的一个程序,该程序不需要干预即可自动开始执行。与tempdb和model 数据库一样,在使用SQL Server时也不要直接修改msdb数据库,SOL Server中的一些程序会自动使用该数据库。例如,当用户对数据进行存储...
Any constraint defined using the aboveALTER TABLEcommand can be dropped using theDROP CONSTRAINTcommand. To drop or remove a foreign key, use the following SQL syntax: ALTER TABLE ORDERS DROP FOREIGN KEY; Types of constraints Foreign keys do not have to be linked specifically to a primary key...
Learn more about the Microsoft.SqlServer.TransactSql.ScriptDom.ForeignKeyConstraintDefinition.ForeignKeyConstraintDefinition in the Microsoft.SqlServer.TransactSql.ScriptDom namespace.
The majority of tables in a relational database system adhere to the foreign key concept. In complex databases and data warehouses, data in a domain must be added across multiple tables, thus maintaining a relationship between them. The concept of referential integrity is derived from foreign key...
Namespace: Microsoft.SqlServer.TransactSql.ScriptDom Assembly: Microsoft.SqlServer.TransactSql.ScriptDom (in Microsoft.SqlServer.TransactSql.ScriptDom.dll)SyntaxC# Kopieren [SerializableAttribute] public class ForeignKeyConstraintDefinition : ConstraintDefinition ...
IdentityValueKeyOption IfStatement IgnoreDupKeyIndexOption IIfCall ImportanceParameterType IndexDefinition IndexExpressionOption IndexOption IndexOptionKind IndexStatement IndexStateOption IndexTableHint IndexType IndexTypeKind InlineDerivedTable InlineFunctionOption InlineResultSetDefinition InPredicate InsertBul...
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