MSSQL：作为文本输出时截断 nvarchar(max)

Question

On MSSQL when I run my query I get the following output when run as Results To Text:

Description                                                                                                                                                                                                                                                      Another Column
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -----------
This is a Description                                                                                                                                                                                                                                            43289

But interestingly there aren't any blanks at all at the end of the string, and the length is also the correct one (without any blanks)

I want to have an output like this:

Description    Another Column
-------------- --------------
My description 543893                                                                                                                                                                                                                                

I've tried rtrim , ltrim , replace , but none is working. The datatype is nvarchar(max) .

Answer 1

As I say, if you really need to do this, you have to do two passes through the data:

create table #t (description nvarchar(max),otherColumn int)
insert into #t(description,otherColumn) values
(N'Short Desc.',21),
(N'Loooooonnnnnngggggg Description',99)

declare @maxLength int
declare @sql nvarchar(max)

select @maxLength = MAX(LEN(description)) from #t

if @maxLength <= 4000
begin
    set @sql = N'SELECT CONVERT(nvarchar(' + CONVERT(nvarchar(4),@maxLength) +
               N'),description) as description'
end
else
begin
    set @sql = N'SELECT description'
end
set @sql = @sql + N',otherColumn from #t'

exec sp_executesql @sql

Result:

description                     otherColumn
------------------------------- -----------
Short Desc.                     21
Loooooonnnnnngggggg Description 99

Even if you use RTRIM , etc, when the system is compiling the query, it doesn't know the nature of the data contained in individual rows ¹ . And so it can only assign the data type nvarchar(max) as the type of the resulting column.

In turn, when SSMS starts to receive the result set, it's informed that the column is an nvarchar(max) . At the point at which it's printing the column headers , it doesn't know the nature of the lengths of the results it will receive, so it just has to adopt a sensible default display width that can cope with any data it receives.

I'd normally leave such format considerations to an actual presentation layer (eg report builder or application), rather than fiddling around and trying to force SQL/SMS to do this sort of formatting.

¹ Eg one of the rows might have the description containing the complete works of Shakespeare, in the original Klingon.

Answer 2

Try this

select Description,len(rtrim(Description)) as count from table

Edit

The actual problem is you set the result mode to text. Change it to grid mode. You will get the correct result

Answer 3

I know this is old, but for anyone who might need it in the future (including myself with how bad my memory is).

I ran into this same problem. Here was the solution I came up with:

SELECT CASE 
        WHEN LEN([Description]) >= 20
            THEN CAST((LEFT([Description], 17) + '...') AS VARCHAR(20))
        ELSE CAST([Description] AS VARCHAR(20))
        END AS [Description]
    ,[Another Column]
FROM [dbo].[YourTableName];

I hope you find this helpful, even though it is a bit of a long-winded way to do it.