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SQL: Primary Keys

sql SQL: Primary KeysSQL: Primary Keys

So if your here on this post your after understanding the mysteries of Primary/Foreign key relationships. Well let me tell you they are an art form not an exacting science something at first you may not appreciate until you deal with your own database schema’s.

SQL Relationships

To understand SQL Relationships it is important that you have covered the previous topics on here so I would recommend looking at the Select Statement  and the where clause before commencing this video.

All databases require primary keys. I have had arguments with people in the past saying “you don’t need them” I normally let them have just enough rope to hang themselves but make sure I have got the scissors on standby to save the day when they discover the need for them when duplicate orders or duplicate customers start cropping up in thier “brand new” database system.

The importance to SQL

I cannot stress to you all the importance of primary keys in SQL…..foreign keys are important but in my line of work (BI) I can quite often get away without using them as much. But Primary Keys are paramount in a database design as they make records unique and indexed. The final point I just mentioned about indexes will be covered in more detail on a separate video as the goal here will be to understand the symbiotic relationship these two elements have for each other.

This video is one of many SQL tutorials on this site click here for more

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943 Comments

  1. Oskar Andersson says
    14 Apr 14 at 7:35am

    Very Usefull for my studies. Thank you!

  2. Mohsin Azam says
    25 Jul 13 at 1:47pm

    as

  3. Ahsan Habib says
    20 Jul 13 at 12:54pm

    thanks

  4. Thamer Dajam says
    08 Mar 13 at 3:30pm

    Thanks
    I’m a student at uni. in Saudi Arabia
    I’m studying from you :p

  5. AmericanMale1953 says
    02 Mar 13 at 10:15pm

    Customers have Orders. Very good thanks.

  6. SwampDragons says
    08 Feb 13 at 11:59am

    Thanks, à bit old these days with low quality. But still informative.

  7. conman2317 says
    21 Jan 13 at 11:02am

    To each their own? FUCK YOU FAGGOT!

  8. PABLOEMCR says
    07 Dec 12 at 12:59pm

    what???????

  9. ddsharper says
    10 Jul 12 at 1:04am

    I love your voice, your inflections and your rambling. So few define their terms, and fewer are so thorough in such a small amount of time. thanks.

  10. ddsharper says
    10 Jul 12 at 1:04am

    [..YouTube..] I love your voice, your inflections and your rambling. So few define their terms, and fewer are so thorough in such a small amount of time. thanks.

  11. TheSnerggly says
    26 Jun 12 at 5:12pm

    Hi – I thought this was great. I like your style and presentation. Helped a moron like me “get it.” I am interested in BI so this was highly useful. Thank you!

    I will probably re-watch.

  12. 26 Jun 12 at 5:12pm

    [..YouTube..] Hi – I thought this was great. I like your style and presentation. Helped a moron like me “get it.” I am interested in BI so this was highly useful. Thank you!

    I will probably re-watch.

  13. AVD072 says
    18 Jun 12 at 5:56am

    Thank you sir that clarified my question

  14. AVD072 says
    18 Jun 12 at 5:56am

    [..YouTube..] Thank you sir that clarified my question

  15. AVD072 says
    18 Jun 12 at 5:56am

    [..YouTube..] Thank you sir that clarified my question

  16. smokenfly514 says
    13 Apr 12 at 2:23pm

    He sounds nothing like Bryan…

  17. 13 Apr 12 at 2:23pm

    [..YouTube..] He sounds nothing like Bryan…

  18. sanwariaamir says
    22 Dec 11 at 8:43am

    YOU ARE A SAVIOR. Thank you so much for the very informative tutorial.

  19. 22 Dec 11 at 8:43am

    [..YouTube..] YOU ARE A SAVIOR. Thank you so much for the very informative tutorial.

  20. 22 Dec 11 at 8:43am

    YOU ARE A SAVIOR. Thank you so much for the very informative tutorial.

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