A foreign key is a relationship between two entities ... These common columns would be used in a join between these tables within a query. From our above example, an ORDER LINE table would likely have ...

If a delete statement affects rows in a foreign key table, those values will be set to NULL when the primary key record is deleted. If an update statement affects rows in the foreign key table ...

Should I set up a foreign key constraint? How would I go about doing this within a table (to tie the parentid field to the folderid field)? Would it cascade through multiple levels? I.e. For the ...