Hey there, SQL learners! I recently stumbled upon a common issue when working with foreign keys in PostgresSQL. I thought I’d share my experience and what I learned from it.
So, I created a parent table called Region with a primary key RegionID. Then, I created a child table called Country with a foreign key RegionID that references the Region table. I inserted values into the Region table from an OrdersCSV file, and everything worked as expected.
However, when I tried to insert values into the Country table, the RegionID column was showing up as null. I was expecting it to autopopulate since it’s referencing the RegionID column from the Region table.
After some research, I realized that I was misunderstanding how foreign keys work. A foreign key is a field in a table that refers to the primary key of another table. It doesn’t autopopulate the value; instead, you need to specify the value when inserting data into the child table.
In my case, I needed to specify the RegionID value when inserting data into the Country table. I can do this by joining the OrdersCSV file with the Region table to get the correct RegionID for each country.
I hope this helps anyone who’s struggling with foreign keys in SQL. Remember, a foreign key is just a reference to a primary key in another table, and you need to specify the value when inserting data into the child table.
Do you have any tips or tricks for working with foreign keys in SQL? Share them in the comments below!