Spaces in WHERE clause for SQL Server [duplicate] - sql

Question

This question already has answers here:
Why the SQL Server ignore the empty space at the end automatically?
(2 answers)
Closed 4 years ago.
I want to find out the records in which a certain column contains exactly one space and nothing else. So I wrote the first of the following queries:
select COUNT(*)
from mytable
where col = ' ' -- One space
select COUNT(*)
from mytable
where col = ' ' -- Two spaces
select COUNT(*)
from mytable
where col = ' ' -- Three spaces
However, all three queries return the exact same records. Does Microsoft SQL Server not distinguish between the amount of spaces? How can I query exactly for one, two or more spaces?

Answer 1

Yes, it ignores trailing spaces in comparisons.
You can try to append a delimiting character.
SELECT count(*)
FROM mytable
WHERE col + 'X' = ' X';

Answer 2

You can combine DATALENGTH clause with your query:
select COUNT(*)
from mytable
where col = ' '
and DATALENGTH(col) = 1

Answer 3

The link posted by Ivan Starostin in the comments of the OP provides a good explanation and I think it deserves a full answer instead of just a comment.
To summarize, try using LIKE instead of equality:
select COUNT(*)
from mytable
where col LIKE ' ' -- one space
And you can also use DATALENGTH to calculate how many bytes are in the field to double-check field length:
select col, DATALENGTH(col)
from mytable;
Please note that DATALENGTH will return a different value if col is a VARCHAR vs NVARCHAR. VARCHAR stores each character as 1 byte where NVARCHAR stores each character as 2 bytes since NVARCHAR is stored in Unicode.

Answer 4

You can replace the single space with a single character (for exampe §) and then put this character in your where condition:
declare #tmp table(col varchar(50))
insert into #tmp values
(' '),
(' '),
(' ')
select COUNT(*) as one_space_count
from #tmp
where replace(col,' ','§')='§'
select COUNT(*) as two_space_count
from #tmp
where replace(col,' ','§')='§§'
select COUNT(*) as three_space_count
from #tmp
where replace(col,' ','§')='§§§'
Results: