Problem using expression in SSIS

  • Hi,

    Below is the expression i am trying to make work :

    substring ("Archive_Full_20120731200002",1, (FINDSTRING( "Archive_Full_20120731200002","Full_", 1)-2))

    Whe I use the exact string(Archive_Full_20120731200002) , I get the required result i.e Archive

    But when I use a variable which contains th same string, the above expression gives the error that

    Substring can allow -ve integer values( Here -2)

    Please help me in this regard. I need to use a variable here and get it work.

    Your help is appreciated!!!

    Thanks

    Devesh

  • Please post the expression which you tried - the one which gives the error.

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

  • Below is the expression to be evaluated:

    Substring (@Variable,1, (FINDSTRING( @Variable,"Full_", 1)-2))

    @Variable is the variable containing the exact string 'Archive_Full_20120731200003'

    But when i used this as a expression, it gives the error that substring does not allow -ve integer values.

    Kindly help.

  • Substring cannot take negative values for the length argument.

  • substring ("Archive_Full_20120731200002",1, (FINDSTRING( "Archive_Full_20120731200002","Full_", 1)-2))

    Then how come the above expression is working where the exact string is used instead of a variable and still negative value is accepted!!! Does it make sense ?

  • Works for me. I suspect that you may have got your variable syntax wrong. Here is my version:

    Substring (@[User::TestString],1, (FINDSTRING(@[User::TestString] ,"Full_", 1)-2))

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

  • Devesh_Srivastava (8/1/2012)


    substring ("Archive_Full_20120731200002",1, (FINDSTRING( "Archive_Full_20120731200002","Full_", 1)-2))

    Then how come the above expression is working where the exact string is used instead of a variable and still negative value is accepted!!! Does it make sense ?

    Good question. I only know that when attempting to put in a negative value for length in a much simpler expression, it errored on negative value of length parameter.

  • herladygeekedness (8/2/2012)


    Devesh_Srivastava (8/1/2012)


    substring ("Archive_Full_20120731200002",1, (FINDSTRING( "Archive_Full_20120731200002","Full_", 1)-2))

    Then how come the above expression is working where the exact string is used instead of a variable and still negative value is accepted!!! Does it make sense ?

    Good question. I only know that when attempting to put in a negative value for length in a much simpler expression, it errored on negative value of length parameter.

    The result of

    FINDSTRING( "Archive_Full_20120731200002","Full_", 1) -2

    is 7. That's not a negative value where I come from 🙂

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

  • Not talking about the result, talking about the length argument.

    I created a simple expression using -2 as length and was unable to save the expression due to "length cannot accept negative number" (okay, not a direct quote, but teh error was specific and when I changed length to positive number, no issues).

  • herladygeekedness (8/2/2012)


    Not talking about the result, talking about the length argument.

    I created a simple expression using -2 as length and was unable to save the expression due to "length cannot accept negative number" (okay, not a direct quote, but teh error was specific and when I changed length to positive number, no issues).

    ??

    The expression I quoted was only the length argument - from the OP's example.

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

  • Phil Parkin (8/2/2012)


    herladygeekedness (8/2/2012)


    Not talking about the result, talking about the length argument.

    I created a simple expression using -2 as length and was unable to save the expression due to "length cannot accept negative number" (okay, not a direct quote, but teh error was specific and when I changed length to positive number, no issues).

    ??

    The expression I quoted was only the length argument - from the OP's example.

    Wouldn't be the biggest shock to find that I am confused, but length is the last argument, and it is -2 to my eyes. I did not actually use OPs expression, I merely made my own very simple Substring on a string existing in my flow and attempted to use a neg number as length.

    No worries, you got him fixed up and I have a giant batch of other fish to fry...

  • Wouldn't be the biggest shock to find that I am confused, but length is the last argument, and it is -2 to my eyes.

    Just as a riposte to your fish-frying comment (you made me hungry while I'm at work! :-)), I'd like to sweep this one up.

    Going back to the OP's example, if you look closely, you'll see that:

    Arg1 = "Archive_Full_20120731200002"

    Arg2 = 1

    Arg3 = (FINDSTRING( "Archive_Full_20120731200002","Full_", 1)-2)

    The absence of evidence is not evidence of absence.
    Martin Rees

    You can lead a horse to water, but a pencil must be lead.
    Stan Laurel

  • Phil Parkin - Thursday, August 2, 2012 11:06 AM

    Wouldn't be the biggest shock to find that I am confused, but length is the last argument, and it is -2 to my eyes.

    Just as a riposte to your fish-frying comment (you made me hungry while I'm at work! :-)), I'd like to sweep this one up.Going back to the OP's example, if you look closely, you'll see that:Arg1 = "Archive_Full_20120731200002"Arg2 = 1Arg3 = (FINDSTRING( "Archive_Full_20120731200002","Full_", 1)-2)

    I am encountering this issue even with correct expression.  Its very strange, if I add +1 to result of findstring function its working fine. 

    SUBSTRING (@[User::var_filename],1, (FINDSTRING(@[User::var_filename] ,"_0", 1)-1))     

    Below is the error.  Var_filename is file name enumerator from for each loop.  If i pass value to this variable  its working fine.

    " The length -1 is not valid for the function substring. The length parameter cannot be negative. Change the length parameter to zero or positive value. "

  • mohanbabu.s - Sunday, November 11, 2018 8:43 AM

    Phil Parkin - Thursday, August 2, 2012 11:06 AM

    Wouldn't be the biggest shock to find that I am confused, but length is the last argument, and it is -2 to my eyes.

    Just as a riposte to your fish-frying comment (you made me hungry while I'm at work! :-)), I'd like to sweep this one up.Going back to the OP's example, if you look closely, you'll see that:Arg1 = "Archive_Full_20120731200002"Arg2 = 1Arg3 = (FINDSTRING( "Archive_Full_20120731200002","Full_", 1)-2)

    I am encountering this issue even with correct expression.  Its very strange, if I add +1 to result of findstring function its working fine. 

    SUBSTRING (@[User::var_filename],1, (FINDSTRING(@[User::var_filename] ,"_0", 1)-1))     

    Below is the error.  Var_filename is file name enumerator from for each loop.  If i pass value to this variable  its working fine.

    " The length -1 is not valid for the function substring. The length parameter cannot be negative. Change the length parameter to zero or positive value. "

    The error is telling you the solution here, however, the problem is the string doesn't contain the expression you're looking for, thus FindString returns 0. 0-1=-1; hence the error.

    Thom~

    Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
    Larnu.uk

  • I am getting this error when i try to evaluate the expression itself.  Ideally it should give this error during run time right?

    SUBSTRING (@[User::var_filename],1, (FINDSTRING(@[User::var_filename] ,"_0", 1)-1))          

    Above is the expression. @[User::var_filename] is the result of for each file enumerator.  I even used the conditional expression check for non zero value from findstring function and only if its greater than zero executing above substring function.  Something like below. 

    (FINDSTRING(@[User::var_filename],"_0", 1) > 0 ? SUBSTRING (@[User::var_filename],1, (FINDSTRING(@[User::var_filename] ,"_0", 1)-1)) : @[User::var_filename] . 

    For above expression, why is that i am getting error in the expression editor itself while evaluating it.

    Kindly advice!!

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