Char with null

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Char with null

tejinder.barnala

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Points: 354
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January 10, 2017 at 10:56 pm

#325179

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Russell Shilling SSCarpal Tunnel Points: 4349 More actions · Answer 1

The answer is clearly wrong. Some of these questions are really questionable.

The

isnull(left(@b,3),'I ô Char') as ba

will also return the string. The left function of @b-2 returns NULL.

So long, and thanks for all the fish,

Russell Shilling, MCDBA, MCSA 2K3, MCSE 2K3

Rune Bivrin SSCrazy Eights Points: 8511 More actions · Answer 2

Russell Shilling (1/10/2017)
The answer is clearly wrong. Some of these questions are really questionable.
The
isnull(left(@b,3),'I ô Char') as ba
will also return the string. The left function of @b-2 returns NULL.

Well, if you'd run the code you'd find it's completely correct.

What's missing in the explanation is the behaviour of ISNULL(). It always derives its return type from the first argument, which in the "ba" case will be char(3) as that is what LEFT() will return.

Just because you're right doesn't mean everybody else is wrong.

sendijunk SSChasing Mays Points: 611 More actions · Answer 3

Good question. Could use a bit more explanation though. Interesting what happens if you replace ISNULL with COALESCE.

Carlo Romagnano SSC-Insane Points: 22668 More actions · Answer 4

sendijunk (1/11/2017)
Good question. Could use a bit more explanation though. Interesting what happens if you replace ISNULL with COALESCE.

The return type depends on "precedence" of types. In this case, the longest string of 8 chars.

Ed Wagner SSC Guru Points: 287026 More actions · Answer 5

And here I was looking for the trick. 😉 Thanks.

Tally Tables - Performance Personified
String Splitting with True Performance
Best practices on how to ask questions

Bob Razumich SSCrazy Points: 2140 More actions · Answer 6

Rune Bivrin (1/10/2017)
Russell Shilling (1/10/2017)
The answer is clearly wrong. Some of these questions are really questionable.
The
isnull(left(@b,3),'I ô Char') as ba
will also return the string. The left function of @b-2 returns NULL.
Well, if you'd run the code you'd find it's completely correct.
What's missing in the explanation is the behaviour of ISNULL(). It always derives its return type from the first argument, which in the "ba" case will be char(3) as that is what LEFT() will return.

And for those inquiring minds that would like a quick link for the ISNULL function, https://msdn.microsoft.com/en-us/library/ms184325.aspx.

akljfhnlaflkj SSC Guru Points: 76202 More actions · Answer 7

I've been caught by these before so had to try it out.

Sean Lange SSC Guru Points: 286590 More actions · Answer 8

Rune Bivrin (1/10/2017)
Russell Shilling (1/10/2017)
The answer is clearly wrong. Some of these questions are really questionable.
The
isnull(left(@b,3),'I ô Char') as ba
will also return the string. The left function of @b-2 returns NULL.
Well, if you'd run the code you'd find it's completely correct.
What's missing in the explanation is the behaviour of ISNULL(). It always derives its return type from the first argument, which in the "ba" case will be char(3) as that is what LEFT() will return.

+1

The question itself I thought was a great question but the explanation skipped the important part about the return datatype from ISNULL.

I look forward to the next question from Tejinder and hope the explanation is as good as the question next time.

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Revenant SSC-Forever Points: 42467 More actions · Answer 9

Iwas Bornready (1/11/2017)
I've been caught by these before so had to try it out.

Me, too.

Thanks, Tejinder!

TomThomson SSC Guru Points: 104773 More actions · Answer 10

Russell Shilling (1/10/2017)
The answer is clearly wrong. Some of these questions are really questionable. The
isnull(left(@b,3),'I Ã´ Char') as ba
will also return the string. The left function of @b-2 returns NULL.

Well, if you'd run the code you'd find it's completely correct. What's missing in the explanation is the behaviour of ISNULL(). It always derives its return type from the first argument, which in the "ba" case will be char(3) as that is what LEFT() will return.

I guess we now have additional evidence of the value (or lack thereof) of MCDBA, MCSA, and MCSE qualifications in filtering CVs.

Tom

tejinder.barnala Old Hand Points: 354 More actions · Answer 11

Revenant - Wednesday, January 11, 2017 9:17 AM
Iwas Bornready (1/11/2017)
I've been caught by these before so had to try it out.
Me, too.Thanks, Tejinder!

thanks everyone for their comments / feedback. i agree explanation of the answer was not upto mark . i will try to be more clear in future