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sql string space padding

Posted on 2014-10-31
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Last Modified: 2014-11-03
I have a char(10) columnA with values:
George
Tom
David

problem is when I take Len(columnA) i get:
5
3
5

how to best change type or pad spaces such that Len(columnA) is always = 10?
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Question by:prequel_server
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15 Comments
 
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Expert Comment

by:Jim Horn
ID: 40416001
Just a thought ... why do you need len(ColumnA) = 10?  
Left or right padded spaces?

If you're doing this for an export, to guarantee ten spaces you can use ColumnA + SPACE(10 - Len(ColumnA))
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Author Comment

by:prequel_server
ID: 40416049
I have a program that only works if the length of that column is 10.
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LVL 69

Expert Comment

by:Éric Moreau
ID: 40416054
you can use DataLength:

DECLARE @x CHAR(10)
SET @x = 'tom'
SELECT @x, LEN(@x), DATALENGTH(@x)

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Expert Comment

by:ScottPletcher
ID: 40416161
LEN(columnA + '.') - 1

The potential issue with DATALENGTH is if you ever change the data type to nchar(10), you'll get "20" as the result instead of "10".


SELECT LEN(columnA + '.') - 1
FROM (
    SELECT CAST('George' AS char(10)) AS columnA UNION ALL
    SELECT CAST('Tom' AS char(10)) AS columnA UNION ALL
    SELECT CAST('David' AS char(10)) AS columnA
) AS test_data
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Author Comment

by:prequel_server
ID: 40416234
Sorry i wasnt clear. My issue is not what len() returns its just that i want my column to be padded with trailing spaces such that it always adds up to 10 chars.

So David should be David and the 5 spaces after it
Tom would have 7 spaces after it
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Expert Comment

by:Jim Horn
ID: 40416237
>So David should be David and the 5 spaces after it
The T-SQL I posted in the first comment does that,
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Expert Comment

by:ScottPletcher
ID: 40416270
LEFT(columnA + SPACE(10), 10)
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Author Comment

by:prequel_server
ID: 40416397
@Scott, I test tried that but unfortunately it doesn't pass the litmus test. of:

LEN (  LEFT(columnA + SPACE(10), 10)  )

still getting various sizes based on the values in the columnA
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Expert Comment

by:Jim Horn
ID: 40416402
>still getting various sizes based on the values in the columnA
Please give us a sample data set of ColumnA values, and what your expected results are.
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Accepted Solution

by:
ScottPletcher earned 500 total points
ID: 40416414
>>
@Scott, I test tried that but unfortunately it doesn't pass the litmus test. of:
 LEN (  LEFT(columnA + SPACE(10), 10)  )
 still getting various sizes based on the values in the columnA
<<

>> My issue is not what len() returns its just that i want my column to be padded with trailing spaces such that it always adds up to 10 chars. <<

I corrected for the LEN() issue earlier, then you said to ignore length and just output 10 chars.

It seems you want contradictory things.  The LEN() function will always ignore trailing spaces.
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Author Comment

by:prequel_server
ID: 40416446
Sorry i didnt know that len() ignors all trailing spaces. Is there another test i use to check?
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Expert Comment

by:ScottPletcher
ID: 40416450
My version is:

SELECT LEN(columnA + '.') - 1

putting a non-space at the end so SQL counts all characters from the column, including trailing spaces.  Adding a '.' of course changes the trailing spaces into embedded spaces, and thus they are no longer ignored.
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Author Comment

by:prequel_server
ID: 40417375
thanks but I don't want an embedded space '.' at the end of the value, I only want enough spaces to fill a 10 char field.
Len() ignores trailing spaces.
is there another length function or nested functions that can count the trailing spaces in a string?
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Expert Comment

by:ScottPletcher
ID: 40419465
I'm subtracting 1 from the length to drop the '.' back out; the '.' is just being used to force a non-space character at the end of the value so that LEN() can count all the other chars.
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Author Comment

by:prequel_server
ID: 40419482
Correct but not exactly what im looking for. I guess i was looking for a test to prove that the field is in fact 10 chars in length.  I thought there would be a function that does count trailing spaces but maybe im wrong. Anyway thanks for your help.
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