Old question but adding answer so that one can get help Its two step process: Suppose, a table1 has a foreign key with column name fk_table2_id, with constraint name fk_name and table2 is referred table with key t2 (something like below in my diagram). table1 [ fk_table2_id ] –> table2 [t2] First step, DROP old … Read more
A foreign key must reference only one parent table. This is fundamental to both SQL syntax, and relational theory. A Polymorphic Association is when a given column may reference either of two or more parent tables. There’s no way you can declare that constraint in SQL. The Polymorphic Associations design breaks rules of relational database … Read more
In one-to-one relation one end must be principal and second end must be dependent. Principal end is the one which will be inserted first and which can exist without the dependent one. Dependent end is the one which must be inserted after the principal because it has foreign key to the principal. In case of … Read more