Skip to main content
Previous sectionNext section

OnDelete

Specifies the action that this foreign key should cause in the current table when a record deleted in the foreign table is referenced by a record in the current table.

Usage

To specify what happens in the current table when a referenced record is deleted in the foreign table, use the following syntax:

ForeignKey keyname(key_props) References pkg.class(ref_index) [ OnDelete = ondelete ];
Copy code to clipboard

Where ondelete is one of the following:

  • noaction (default) — When an attempt is made to delete a referenced record in the foreign table, the attempt fails.

  • cascade — When a referenced record is deleted in the foreign table, the referencing record in this table is also deleted.

  • setdefault — When a referenced record is deleted in the foreign table, the reference to the foreign table in the referencing record is set to its default value.

  • setnull — When a referenced record is deleted in the foreign table, the reference to the foreign table in the referencing record is set to null.

Description

When a row is deleted in the foreign table, all referencing tables with a foreign key constraint on the foreign table are checked to see if any row references the row being deleted. If any such references are found, the OnDelete action takes effect.

Default

The default is noaction.

See Also