I want to update a varchar column with the update clause like this:
UPDATE ptl SET version=NULL WHERE version = 'a';
Query OK, 0 rows affected
What looks like an "a" would not seem to be solely an
'a'. This can be for a variety of reasons. Start with:
select length(ptl.version), ptl.version from ptl where version like '%a%' order by length(ptl.version);
You can see the length of the version being returned.
You might have other characters such as spaces in the value. Or, you might have a utf character that happens to look like a lower-case a. In the latter case, the above may not return anything.