How to read a text file

Question

I've inherited a horrible stored proc to load an XSL file from a text file into one TEXT column in one row. It BULK INSERTs into a temporary table and then cursors through that somehow appending the lines together into a TEXT variable using TEXTPTR and UPDATETEXT. The whole thing is in a transaction. What could go wrong?

Well, it's suddenly started occasionally not loading some of the start of the file. No errors, it just sometimes misses off the first n bytes (always the same number of bytes).

I have a recipe like this that works:

create table #FileContents 
(
    LineNumber int identity
    , LineContents nvarchar(4000)
);

declare @FileName   varchar(255);
declare @NewLine    char(2) = char(13) + char(10);
declare @CmdLine    varchar(300);
declare @XSL       varchar(max);

set @FileName = '<filename>'

set @CmdLine = 'type ' + @FileName;

insert #FileContents
exec master.dbo.xp_cmdshell @CmdLine;

select @XSL = isnull(@XSL, '') + @NewLine + isnull(LineContents, '')
from      #FileContents
order by LineNumber;

Is there a cleaner way? Maybe one that doesn't use xp_cmdshell?

Answer 1

0

Here is the sample showing how to insert the guts of the file to the table without using the xp_cmdshell:

create table #FileContents 
(
    LineNumber  int identity (1, 1),
    LineContents  nvarchar(4000)
);

insert into #FileContents
select f.BulkColumn 
    from openrowset
    (
        bulk 'C:\Useless\Temp\some_file.txt',
        single_clob 
    ) f;

select * from #FileContents;

The results display (because this what was in the file):

LineNumber  LineContents
----------- ------------
1           Hello, Jerry
            Hello, Newman

Of course it goes without saying that the file path is relative to the server.

Oleg

answered Jul 26 '10 at 08:48 AM

Oleg
15.4k ● 1 ● 4 ● 24

That works like a charm. Thanks, Oleg.

Jul 26 '10 at 09:07 AM David Wimbush

@David Wimbush Thank you. In my answer, the path to the file is hardcoded because openrowset will not accept a path as a parameter. This means that should the file path be a parameter, the insert into select from should be spelled out into a varchar variable which can be fed to the execute in order to bypass this limitation of the openrowset. For example,

 declare @file_path nvarchar(50); -- declare the size as needed (no limit) declare @sql nvarchar(500);

select  @file_path = 'C:\Useless\Temp\some_file.txt',  @sql = 'insert into #FileContents  select f.BulkColumn  from openrowset  (  bulk ''' + @file_path + ''',  single_clob  ) f;';

exec (@sql);

Jul 26 '10 at 09:15 AM Oleg

So I discovered! But you put me on the right track. Thanks.

Jul 26 '10 at 02:41 PM David Wimbush

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Answer 2

0

If you can create a CLR assembly with EXTERNAL_ACCESS, then I would go that route. Given that you have a nvarchar(4000) column, you will want to split larger text files into smaller chunks.

You will also want it not to epic fail on Unicode.

A CLR table function could be a neat way to achieve the above two without causing the massive hole that xp_cmdshell does.

answered Jul 26 '10 at 08:44 AM

Matt Whitfield ♦♦
29.2k ● 56 ● 63 ● 87

Thanks Matt. +1 because I think this is probably the technically superior solution. But this is a live problem a quick fix is needed so I'm going with Oleg's answer in this case.

Jul 26 '10 at 09:06 AM David Wimbush

@David Wimbush - fair play - but do remember that if you need Unicode support (which the nvarchar suggests) then you will need to do it properly...

Jul 26 '10 at 09:13 AM Matt Whitfield ♦♦

@Matt Whitfield +1 This is a very sound solution! As a matter of fact, you gave me an excellent idea on the task I am working right now. Thank you.

Jul 26 '10 at 09:33 AM Oleg

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How to read a text file

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