Access foreign key not updating

24-Oct-2019 06:05

CASCADE cannot be specified if a timestamp column is part of either the foreign key or the referenced key.

ON DELETE CASCADE cannot be specified for a table that has an INSTEAD OF DELETE trigger.

If an attempt is made to delete the row in a primary key table or to change a primary key value, the action will fail when the deleted or changed primary key value corresponds to a value in the foreign key constraint of another table.

To successfully change or delete a row in a foreign key constraint, you must first either delete the foreign key data in the foreign key table or change the foreign key data in the foreign key table, which links the foreign key to different primary key data.

This column becomes a foreign key in the second table. Sales Order Header table has a foreign key link to the Sales.

Sales Person table because there is a logical relationship between sales orders and salespeople.

In a foreign key reference, a link is created between two tables when the column or columns that hold the primary key value for one table are referenced by the column or columns in another table.

Sales Person table, and the salesperson's ID is used for sales orders in the Sales.

Sales Order Header table, the relational integrity between the two tables is broken; the deleted salesperson's sales orders are orphaned in the Sales Order Header table without a link to the data in the Sales Person table. The constraint enforces referential integrity by guaranteeing that changes cannot be made to data in the primary key table if those changes invalidate the link to data in the foreign key table.

As shown in the following illustration, the Product ID and Vendor ID columns in the Purchasing.

Product Vendor table form a composite primary key constraint for this table.

In a foreign key reference, a link is created between two tables when the column or columns that hold the primary key value for one table are referenced by the column or columns in another table.

Sales Person table, and the salesperson's ID is used for sales orders in the Sales.

Sales Order Header table, the relational integrity between the two tables is broken; the deleted salesperson's sales orders are orphaned in the Sales Order Header table without a link to the data in the Sales Person table. The constraint enforces referential integrity by guaranteeing that changes cannot be made to data in the primary key table if those changes invalidate the link to data in the foreign key table.

As shown in the following illustration, the Product ID and Vendor ID columns in the Purchasing.

Product Vendor table form a composite primary key constraint for this table.

SQL Server 2016 (13.x) increases the limit for the number of other table and columns that can reference columns in a single table (incoming references), from 253 to 10,000.