LEN function not including trailing spaces in SQL Server

This is clearly documented by Microsoft in MSDN at http://msdn.microsoft.com/en-us/library/ms190329(SQL.90).aspx, which states LEN "returns the number of characters of the specified string expression, excluding trailing blanks". It is, however, an easy detail on to miss if you're not wary.

You need to instead use the DATALENGTH function - see http://msdn.microsoft.com/en-us/library/ms173486(SQL.90).aspx - which "returns the number of bytes used to represent any expression".

Example:

SELECT 
    ID, 
    TestField, 
    LEN(TestField) As LenOfTestField,           -- Does not include trailing spaces
    DATALENGTH(TestField) As DataLengthOfTestField      -- Shows the true length of data, including trailing spaces.
FROM 
    TestTable

You can use this trick:

LEN(Str + 'x') - 1

I use this method:

LEN(REPLACE(TestField, ' ', '.'))

I prefer this over DATALENGTH because this works with different data types, and I prefer it over adding a character to the end because you don't have to worry about the edge case where your string is already at the max length.

Note: I would test the performance before using it against a very large data set; though I just tested it against 2M rows and it was no slower than LEN without the REPLACE...

"How do I include the trailing spaces in the length result?"

You get someone to file a SQL Server enhancement request/bug report because nearly all the listed workarounds to this amazingly simple issue here have some deficiency or are inefficient. This still appears to be true in SQL Server 2012. The auto trimming feature may stem from ANSI/ISO SQL-92 but there seems to be some holes (or lack of counting them).

Please vote up "Add setting so LEN counts trailing whitespace" here:

https://feedback.azure.com/forums/908035-sql-server/suggestions/34673914-add-setting-so-len-counts-trailing-whitespace

Retired Connect link: https://connect.microsoft.com/SQLServer/feedback/details/801381