Join issue

  • I had one of our programmers come to me this morning and she is trying to update some information in one of our tables. They have the changes in an Excel spreadsheet and have imported it into a work table in SQL. The fields that they are trying to join on are identical. Both are char(14). (I realize that both of these fields should probably be an int but dealing with a legacy system.) However, the following query won't return any results:

    SELECT *

    FROM dm_prod dm_p JOIN wk_BricsCad w ON dm_p.SsProdid = w.SsProdid

    If I open the work table and edit the the ssprodid field and manually delete the extra spaces at the end of the field out and then run the query I get one match.

    So, logically, I figured why not run an update to the work table and trim the ssprodid field. That should get the query to match on all 700+ records. Still only one match.

    Any ideas as to what is going on here?

  • Running:

    Update table

    Set char_field = Rtrim(char_field)

    Does not actually trim as the char data type is fixed width so the data is right padded with spaces. Now changing the data type to varchar(14) and then running the RTRIM will remove spaces on the end.

    You could do this in your join:

    Select

    From

    tableA A Join

    tableB B On

    RTrim(A.char_field) = RTrim(B.char_field)

    Of course this is likely to cause a table scan.

  • The characters are probably some other 'invisible' characters - like tabs or returns.

    Use something like this to figure out what the ascii values are...

    select distinct ascii(substring(MyColumn, number, 1)) from myTable cross join

    (select distinct number from master.dbo.spt_values where number between 0 and 14) a

    Use something like this to update them (this could be faster but it will do the job). Alternatively you can hard-code the replaces based on the results of the previous query.

    select 0 --to set @@rowcount

    while @@rowcount > 0

    update myTable set MyColumn = stuff(MyColumn, patindex('%[^0-9]%', MyColumn), 1, '') where MyColumn like '%[^0-9]%'

    Ryan Randall

    Solutions are easy. Understanding the problem, now, that's the hard part.

  • Jack Corbett (4/25/2008)

    Got me again! 😀

    Ryan Randall

    Solutions are easy. Understanding the problem, now, that's the hard part.

  • Have you tried casting the columns as Int in your join?

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  • Yes, I have. I get the following when doing that.

    Msg 245, Level 16, State 1, Line 1

    Conversion failed when converting the varchar value '16954797      ' to data type int.

  • Thanks Ryan. I ran what you posted and believe it worked. Thanks for your help.

    Is there a way when importing text files to keep those "invisible" characters out to begin with?

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