On 23/01/2013 14:02, John English wrote:
I want to select all rows from a table where a varchar column is a zero-length string. Of course this works: SELECT * FROM my_table WHERE my_col=''; but I would have expected this to work too: SELECT * FROM my_table WHERE my_col NOT LIKE '%_%'; The first query returns all the expected rows; the second returns zero rows.
Oops, posted too hastily. The actual query used CHAR(my_col), since I don't know in advance the type of the column I'm filtering on, and this returns a string space-padded to 16 characters from an empty string. Adding TRIM() to this fixed the problem.
Apologies for wasting your bandwidth... -- John English
