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Using Set Theory to Understand SQL Joins


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21 replies to this topic

#13 mendim.

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Posted 26 February 2009 - 10:55 AM

Nice Tuto , Winged +rep .
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#14 Brandon W

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Posted 26 February 2009 - 01:30 PM

Did you ever teach SQL to any class?
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#15 WingedPanther73

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Posted 26 February 2009 - 04:55 PM

No. I didn't learn SQL until after I was no longer teaching.
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#16 Brandon W

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Posted 27 February 2009 - 01:41 AM

Oh OK. Do you have any formal qualifications for programming?
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#17 WingedPanther73

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Posted 27 February 2009 - 09:06 AM

Ummm... I took a couple classes on Pascal... in 1991.
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#18 gaylo565

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Posted 27 February 2009 - 10:10 AM

I like this...I do plenty of SQL at work and spend lots of time thinking about what the querry I'm writing will really do. I have spent hours waiting for a querry to finish just to find out it didn't return the data that I expected. This is the sort of stuff that most probably wont master untill after lots of practice but the tutorial is a great start.
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#19 Brandon W

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Posted 27 February 2009 - 02:01 PM

Wow, but that is the good thing about the IT area ;)
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#20 sactiw

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Posted 02 September 2010 - 01:56 AM

This good and another a good explanation with venn diagram could be found here:

explanation of SQL JOINS using Venn diagrams
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#21 Humi

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Posted 23 September 2010 - 11:09 AM

This has been very useful for me.. Thank you so much.. Its is well explained and easy to understand... I have been struggling with the joins for quite some time now.. After reading and trying i am quite clear now.. Can you please continue with your next session..
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#22 WingedPanther73

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Posted 23 September 2010 - 12:42 PM

To be honest, I just wrote this as a stand-alone, because I know joins DO cause confusion. It's the only part of SQL that I've seen that seems to scramble people's heads, except maybe NULLs.
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