Question

I’m having problems with a table copy erroring due to a primary key constraint when the primary key is on the new table. In doing some investigation by not setting a primary key I was able to find a duplicate row in my source table, still unsure how it got in there but what I’m more curious about is the rest of what I found.

Here goes:

I have a SQL query that selects the full table and returns the following:

SELECT *
 FROM search_term_suggest
 order by search_term

you can see the value is duplicated and I had to scroll through the table to find it.

But when I limit my query to:

SELECT *
 FROM search_term_suggest
 where search_term = 'b'

you can see it filters out the first value. There are no triggers on the database or anything I can see that would limit the select query.

I’m running SQL 2008 r2. Any help is greatly appreciated. The database I’m copying the table to is a SQL 2000 database and when selecting using the same queries as above I get the results I would expect.

EDIT: search_term is a varchar(100), search_term_suggest is a table not a view.

Answer 1

My guess: search_term is a CHAR/NCHAR and has trailing spaces (or trailing spaces are being considered for other reasons). Try:

WHERE RTRIM(search_term) = 'b';

You may also need to eliminate tabs/carriage returns, which aren’t affected by trim operations.

WHERE LTRIM(RTRIM(REPLACE(REPLACE(REPLACE(search_term,
  CHAR(9), ''), CHAR(10), ''), CHAR(13), ''))) = 'b';

Note that both of the above queries preclude using an index, so if there is an index on search_term you should probably rebuild it after changing the column to varchar or nvarchar and making sure that padding settings and whitespace aren’t causing the problem.

Other guesses: as @Dems points out, check the length of both columns on the first query. Also try changing your where clause to the following, for investigation purposes only:

WHERE search_term LIKE 'b%'
  AND LEN(search_term) > 1;

If you get any result there, then you can say:

DECLARE @val VARCHAR(100), @i INT;

DECLARE c CURSOR LOCAL STATIC READ_ONLY FAST_FORWARD 
  FOR SELECT search_term FROM dbo.search_term_suggest
  WHERE search_term LIKE 'b%'
    AND LEN(search_term) > 1;

OPEN c;

FETCH NEXT FROM c INTO @val;

WHILE @@FETCH_STATUS = 0
BEGIN
  SET @i = 1;
  PRINT '-----' + @val + ' (' + RTRIM(LEN(@val)) + ')';
  WHILE @i <= LEN(@val)
  BEGIN
    PRINT SUBSTRING(@val, @i, 1) + ' = ' + ASCII(SUBSTRING(@val, @i, 1));
    SET @i = @i + 1;
  END

  FETCH NEXT FROM c INTO @val;
END
CLOSE c;
DEALLOCATE c;

This will help you troubleshoot what is in that column aside from the b – it may be whitespace you haven’t checked for (e.g. a tab or carriage return) or other non-printing characters.