Printing Lengths

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Printing Lengths

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SanDroid SSChampion Points: 10068 More actions · Answer 1

Rahul The Dba (12/13/2010)
thanks
n i promise i will keep ur words in mind, nxt time i post some questions..

Rahul,

We are not able to tell who these comments are for if you do not post a quoted reply like this one.

😎 Or at the very least include thier name in the post.

--------

I have.

Who has ever been called a "Top Poster"?

UMG Developer SSChampion Points: 13482 More actions · Answer 2

Thanks for the interesting question. Though I hope questions like this wouldn't be necessary, and that people would always specify a length on variables to keep themselves out of trouble.

SQLRNNR SSC Guru Points: 281334 More actions · Answer 3

Thanks for the question.

Jason...AKA CirqueDeSQLeil
_______________________________________________
I have given a name to my pain...MCM SQL Server, MVP
SQL RNNR
Posting Performance Based Questions - Gail Shaw[/url]
Learn Extended Events

ziangij SSCertifiable Points: 7988 More actions · Answer 4

good one, thanks Rahul...:-)

declare @myvariable as varchar, @len1 varchar, @len2 varchar

set @myvariable = 'hi hello how are you'

set @len1 = (select datalength(cast(@myvariable as char)))

print @len1

set @len1 = (select datalength(cast(@myvariable as varchar)))

print @len1

set @len2 = (select datalength(convert(char, @myvariable)))

print @len2

set @len2 = (select datalength(convert(varchar, @myvariable)))

print @len2

The above code generates output as

*

1

*

1

difference of char, varchar datatypes...:-)

Hardy21 SSCrazy Eights Points: 9708 More actions · Answer 5

Hardy21

SSCrazy Eights

Points: 9708

December 14, 2010 at 12:54 am

#1262057

Nice question. Learn something new today...

Thanks

Rahul The Dba SSChasing Mays Points: 647 More actions · Answer 6

Hardy21 (12/14/2010)
Nice question. Learn something new today...

thankss

[font="Comic Sans MS"]Rahul:-P[/font]

Carlo Romagnano SSC-Insane Points: 22601 More actions · Answer 7

This is an old kind of COBOL bug:

using bad datatype to hold integer:

01 IDX PIC 9.

PERFORM LBL VARYING IDX BY 1 UNTIL IDX > 10.

Endless loop

michael.kaufmann SSCrazy Points: 2816 More actions · Answer 8

Thanks for the question, Rahul.

But personally I find the explanation somewhat confusing, specifically the last paragraph where it reads:

It is '*' because when we convert character or binary expressions to an expression of a different data type, data can be truncated, only partially displayed, or an error is returned because the result is too short to display. * means the result length too short to display

In regards to the default length when n is undefined, it doesn't make a difference whether you use CAST or CONVERT.

@length1 prints 1 because no conversion is carried out (varchar = varchar).

@length2 prints * because the result (30, due to the conversion from varchar to char) actually is too long to fit into a column implicitely set to varchar(1) = by not specifying the length in the variable declarartion.

Regards,

Michael

Paul White SSC Guru Points: 150467 More actions · Answer 9

I took a stab at 1,30. So it was 1,*. Ha, very good. I'll have forgotten this again in half an hour, and I still won't care 😀

Paul White
SQLPerformance.com
SQLkiwi blog
@SQL_Kiwi

UMG Developer SSChampion Points: 13482 More actions · Answer 10

SQLkiwi (12/18/2010)
I took a stab at 1,30. So it was 1,*. Ha, very good. I'll have forgotten this again in half an hour, and I still won't care 😀

Will you have forgotten it again because you always specify the length and this isn't an issue? (Unless of course you are working on code written by somebody that doesn't.)

Paul White SSC Guru Points: 150467 More actions · Answer 11

UMG Developer (12/18/2010)
Will you have forgotten it again because you always specify the length and this isn't an issue? (Unless of course you are working on code written by somebody that doesn't.)

Yes. If I do have to work on code written by someone that thought it was clever to omit lengths, I always have to look it up to be sure.

Paul White
SQLPerformance.com
SQLkiwi blog
@SQL_Kiwi

SQLWinther SSCertifiable Points: 6294 More actions · Answer 12

Thanks for the question! Learned something today. I knew about the default length for char/varchar, but not the convert issue. An important sample to show why you shouldn't omit default values or on mandatory statements.

/Håkan Winther
MCITP:Database Developer 2008
MCTS: SQL Server 2008, Implementation and Maintenance
MCSE: Data Platform

zymos SSCommitted Points: 1960 More actions · Answer 13

zymos

SSCommitted

Points: 1960

February 27, 2012 at 10:14 am

#1452180

Thanks for the question on the data types.