What is the difference between Primary Key, Composite Key and Foreign Key?

[@lolaoduguwa5957]

This was a very good explanation. Thank you x

[@free2idol1]

Hi,
thanks for your tutorial...
I am trying to apply what you said in my current task of my project and I'm having a dilemma.
Please help me with this.
I have 3 tables:
table Title:
- id
- name
table TitleRank:
- id
- name
- title_id
- rank
table UserTitleRank
-id
-name
-user_id
I want to create FK at `UserTitleRank` to reference the `title_id` and `rank` at `TitleRank`.
I have 2 choices:
1/ create composite FK `title_id` and `rank` at `UserTitleRank` table referencing `title_id` and `rank` of `TitleRank`
2/ create single FK `title_rank_id` referencing `id` of `TitleRank`
Which one is better?
What is the pros and cons of each and what is the implication and context I should take into account to select one over another?
Thank you.

[@nandinimukherjee7617]

Nice explanation... Thanks😊

[@passportbro904]

amazing

[@Imyashmita...]

Your explanation is very helpful for me... Thanks and keep it up 😇

[@hasanmougharbel8030]

Hey there, keep up the good work in this channel.
I have a general enquiry as a new sql learner.
What is the major difference between primary key and unique unique.. In what way they are different inside sql syntax?
Thanks for taking care of this.

[@learnwithpriyankams]

Here you go - ruclips.net/video/Obi3uL-5PR0/видео.html and check my channel for separate videos that show what is a unique key with a demo in it here - ruclips.net/video/WsIgk44eWvc/видео.html and Primary key demo here - ruclips.net/video/M-7fKheZByQ/видео.html

[@sujatajamale5761]

U were stucking fumbling alot while explaining. It is distracting Lister. So just try to improve that