SQL Server sort order with nonprintable characters

问题

I have a scalar value function that returns a varchar of data containing the ASCII unit seperator Char(31). I am using this result as part of an Order By clause and attempting to sort in ascending order.

My scalar value function returns results like the following (nonprintable character spelled out for reference)

ABC
ABC (CHAR(31)) DEF
ABC (CHAR(31)) DEF (CHAR(31)) HIJ

I would expect that when I order by ascending the results would be the following:

ABC
ABCDEF
ABCDEFHIJ

instead I am seeing the results as the complete opposite:

ABCDEFHIJ
ABCDEF
ABC

Now I am fairly certain that this has to do with the non-printable characters, but I am not sure why. Any idea as to why that is the case?

Thanks

回答1:

The sortorder can be influenced by your COLLATION settings. Following script, explicitly using Latin1_General_CI_AS as collation orders the items as you would expect.

;WITH q (Col) AS (
    SELECT 'ABC' UNION ALL
    SELECT 'ABC' + CHAR(31) + 'DEF' UNION ALL
    SELECT 'ABC' + CHAR(31) + 'DEF' + CHAR(31) + 'HIJ'
)
SELECT  *
FROM    q   
ORDER BY
        Col COLLATE Latin1_General_CI_AS

What collation are you using? You can verify your current database collation settings with

SELECT DATABASEPROPERTYEX('master', 'Collation') SQLCollation;

回答2:

I am able to duplicate this behavior in SQL Server 2008 R2 with collation set to SQL_Latin1_General_CP1_CI_AS.

If you cannot change your collation settings, set the field to nvarchar instead of varchar. This solved the issue for me.

来源：https://stackoverflow.com/questions/11107104/sql-server-sort-order-with-nonprintable-characters

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sql

sql-server

tsql

ascii