Yes, but this is not the problem.

The exact problem is that for SQL norm if you compare two string with different lengths the first thing done by SQL is to make them to the same length by adding trailing spaces.

So, if your query compares string1 'a' and string2 'a ', string1 is first converted to 'a ' then compared to string2, and now the two string are the same.

Finally and fortunately, if the field is a UNIQUE INDEX it is not possible to have 'a' and 'a ' in two different rows. If it is not a UNIQUE INDEX field, then you will have to use RTRIM, LTRIM and LEN function with an extra character like LEN('a'+'#')=2 and LEN('a '+'#')=3.

Len('a') and len('a ') give ...1

What you must keep in mind is :

Remove trailing spaces before insertion !