How to join two tables in MySQL using foreign key?
I need to show the table employees, but instead of department_id (showing the IDs of the departments) I need to show the actual departments name, so in place of department_id, i need to place departments.department. How should I do this? You just have to use a inner join between your two tables like this:
How to create a table with a foreign key?
I have an issue with my SQL syntax when creating a table with a set of Foreign Key (Orig_Dept_ID & New_Dept_ID) that references Dept_ID in the Department Table. Could someone please advise on how I should go about doing this?
Can a column name be a foreign key?
There are columns and there are foreign keys (FKs) and there are constraints. You can have a column name in a table regardless of other tables. A FK is a referencing table and column set and a referenced table and column set. All the names together identify a FK.
Which is the primary key of the joining table?
The PRIMARY KEY of the joining table is a natural one, make up of the PK s of both of the entities that comprise it. Make a FOREIGN KEY constraint for each separately. Thanks for contributing an answer to Database Administrators Stack Exchange!
Is it OK to use select * in MySQL?
You should not use SELECT * and just take the fields you really want if it’s only to take a screenshot of the table values. Thanks for contributing an answer to Stack Overflow!
Why do I need separate link table in MySQL?
Because it is a PITA to extract those comma separated values out agian in SQL. Instead you should add a separate link table to represent the relationship between categories and movies, like so: Note that the last query only works if there are 2 or fewer categories per movie.
Is there a way to fake direct join in MySQL?
Normalisation exists to solve this problem. It should be covered pretty well in your MySQL book if it’s worth its salt. If you really insist, though, you can fake the direct join by cross-matching with FIND_IN_SET (which conveniently expects a comma-delimited string of items).