i have a problem transfering my er model into sql developer
i have 2 entities in my er model
and an Entity
it is a 1:n relationship because a nation has several players
now is the problem how to create this model with the SQL Developer
I just created the 2 tables and now i dont know how to make the relationship, how to set the foreign key in the table player
my first try was to rightklick on player --->constraint -->add foreign key
the name should be nation_id_fk
and the referencetable and referencecolumn is clear, but why do i need to add the column name of the existing table ?
what do i need to choose ? i want a new column, the column "nation_id_fk" but there are just the choices nation_id , name , flag..
alter table player
add constraint nation_id_fk
foreign key (nation_id)
references nation( nation_id )
This means that the column player.nation_id references the column nation.nation_id. You don't need a new column as the relevant columns already exist.
In the add constraint dialog nation and nation_id are the referenced table and column.
Note that nation.nation_id needs to be a primary key or a unique queue.