When the foreign key constraint is disabled the constraint is marked as not trusted. Replace the table name and constraint name. To disable a SQL foreign key constraint, we need to use below statement. To modify the existing foreign key using T-SQL we must drop the foreign key constraint first and then re create it with new changes.ĭisabling and enabling the foreign key constraint Disable constraint NO ACTION – If the update or delete on primary key column fails the constraint rule then the change is rolled back ![]() Foreign keys are stored on one side of the relation. If the default constraint is not defined and column is not nullable then below error occurs and the change on primary key column is rolled back In SQL, you use a foreign key to create a relation between two tables. If the default constraint is not defined and column is nullable then foreign key column value is set to NULL. SET DEFAULT- Sets the default value on foreign key column when primary key value is updated or deleted. Click the relationship in the Selected Relationship list. In the Foreign-key Relationships dialog box, click Add. From the Table Designer menu, click Relationships. If the column does not allow null values, the update/delete on primary key column fails and throw error In Object Explorer, right-click the table that will be on the foreign-key side of the relationship and click Design. ![]() ![]() SET NULL – Sets the SQL foreign key column value to null when the primary key value is either deleted or updated to a new value. Similarly, we have the following actions. And then for the data type, Ill have to write this phrase, INTEGER PRIMARY KEY which signals to the database that it should treat this as the row. Update Dept set DeptID = 3 where DeptID = 2Īfter executing the above statement, we can see DeptID is updated to 3 for records having DeptID 2 in the child table as well.
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