ALTERTABLE[dbo].[Documents]WITHCHECKADDCONSTRAINT[FK_Documents_Parent]FOREIGNKEY(LinkedDocumentId) REFERENCES[dbo].[Documents]([Id]) END 关系FK_Documents_Parent不存在。 但是,它将引发错误: The ALTER TABLE statement conflicted with the FOREIGN KEY SAME TABLE constraint"FK_Documents_Parent". The confli...
INSERT statement conflicted with COLUMN FOREIGN KEY SAME TABLE constraint Insert turkish character problem Insert Word document file into SQL Server table INSERT...SELECT command with a timestamp column Inserting .png file as VARBINARY (no c#) Inserting a large amount of data in SQL table Insertin...
create table parent2 (i1 int not null primary key, i2 int); create table child (i1 int not null primary key, i2 int, i3 int); create table grandchild (i1 int not null primary key, i2 int, i3 int); alter table parent add constraint fkp1 foreign key (i2) references grandparent...
SQL>Constraint>Foreign Key A foreign key is a column (or columns) that references a column (most often the primary key) of another table. The purpose of the foreign key is to ensure referential integrity of the data. In other words, only values that are supposed to appear in the databas...
Is the table referenced by the FOREIGN KEY constraint. ref_column Is a column or list of columns in parentheses referenced by the new FOREIGN KEY constraint. ON DELETE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } Specifies what action happens to rows in the table that is altered, ...
1.4:Adding aForeign Key to an Existing Table 1.5:Allowing Cascading Changes in Foreign Keys 2:Surrogate Keys 3:Constraints 3.1:Creating a Unique Constraint 3.2:Using CHECK Constraints 1:Keys A primary keyis aspecial type of constraint, which identifies asingle column or set of columns, which in...
A FOREIGN KEY in one table points to a PRIMARY KEY in another table. On whichever column you put FOREIGN KEY constraint then the values in that column must refer to existing values in the other table.
Corresponding rows are deleted from the referencing table if that row is deleted from the parent table. SET NULL All the values that make up the foreign key are set to NULL when the corresponding row in the parent table is deleted. For this constraint to execute, the foreign key columns mu...
The referenced unique or primary key constraint on the parent table or view must already be defined. 引用唯一或主键约束,必须是父表中已经定义的。 A composite foreign key cannot have more than 32 columns. 外键的组合列不能超过32列。 The child and parent tables must be on the same database. ...
] type_name [ (precision [ , scale ]) ] <column_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED | NONCLUSTERED HASH WITH ( BUCKET_COUNT = bucket_count ) } [ ( <column_name> [ ,... n ] ) ] | [ FOREIGN KEY ] REFERENCES [ schema_...