What will happen if we try to add a default value constraint on a foreign key where that default value does not exist in the table ?
Example:
Table_Person
has Gender
column as foreign key Table_Gender
has rows with values '1' and '2' What will happen if I make default constraint in Table_Person
for Gender
column with default value = '3' ?
Will it be created or throw an error? And reason for that?
It will depend highly on what concrete database system (RDBMS) you're using.
For SQL Server :
You can create both tables, including the default constraint in Table_Person
You can insert rows into Table_Person
that explicitly define a value for Gender
which is 1 or 2
You can not however insert rows into Table_Person
that omit the value for Gender
and thus would get the default value of 3 inserted - since that violates the FK constraint
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