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Searching Float columns with LIKE - Float to string cast

Posted on 2007-03-20
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Last Modified: 2010-05-18
Hi there,
I have a float column that I need to search with LIKE /using of course some kind of string cast). The problem is that DB2 float to string cast, casts to scientific notation. I have tried casting to a decimal first, this helps, but pads the LHS with 0s. This causes problem when the numbers are negative.  I have a column with the following value '-129.543'. I would like to be able to search with the following examples:
-129.5
9.54
9.543
-1
etc.
Something like
select char(decimal(wkz, 12, 4)) from lst.klk where char(decimal(wkz, 12, 4)) like '%129.5%'
works for all examples except those with a minus sign.
0
Comment
Question by:davelane
  • 4
  • 2
7 Comments
 
LVL 37

Expert Comment

by:momi_sabag
ID: 18757556
so how about

select case
   when wkz > 0 then char(decimal(wkz, 12, 4))
   else   "-"||char(decimal(abs(wkz, 12, 4)))
   end
from lst.klk
where case
   when wkz > 0 then char(decimal(wkz, 12, 4))
   else   "-"||char(decimal(abs(wkz, 12, 4)))
   end  like '%129.5%'

this way, if the number is positive you use your solution, if the number is negative you just convert it to positive and add the minus sign before the string

momi
0
 
LVL 50

Expert Comment

by:Lowfatspread
ID: 18758406
why cant you just do

where column between yourvalue - 0.000001 and yourvalue + 0.000001

preferably geting the range sorted out prior to the statement
so that the select can just do a between ...

e.g.

select yourvalue - 0.000001 , yourvalue + 0.000001
  into    fromvalue,tovalue
 from sysibm.sysdummy1

select ...
  from yourtable
 where yourcolumn between fromvalue and tovalue

?
0
 

Author Comment

by:davelane
ID: 18760722
Hi,
I'm looking into the first suggestion. Thanks for the replies. It's a long story about why we need to be able to do this, the main point being we offer a search capability over a variety of columns of data in a table and we want to offer a consistent approach in every column.The users have gotten used to remembering only parts of the values in order to find stuff.

The search entry 456 should find both of the following:
12345.23
45678.28
Therefore a range is pretty much out of the question.

There must be some way of casting a float to a string and get the result in non-scientific notation?

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Author Comment

by:davelane
ID: 18762710
Hi there momi_saba,
I don't quite follow your suggestion. For the value -1.23 the SQL Statement
select decimal(wkz, 12, 4) from klk return the following:
-000000000001.2300
So doing the following '-' || char(decimal(abs(wkz), 12, 4)) gives out the exact same value. Thus the statement:
select
      case
            when
                  wkz >= 0
            then
                  char(decimal(wkz, 12, 4))
            else  
                  '-' || char(decimal(abs(wkz), 12, 4))
         end,
      char(decimal(wkz, 12, 4))
from lst.klk
where
      case
            when
                  wkz >= 0
            then
                  char(decimal(wkz, 12, 4))
            else  
                  '-' || char(decimal(abs(wkz), 12, 4))
         end <>
      char(decimal(wkz, 12, 4))
returns no values
0
 

Author Comment

by:davelane
ID: 18770056
Upping points
0
 
LVL 37

Accepted Solution

by:
momi_sabag earned 500 total points
ID: 18770450
Hi

i think i got a solution for you
assume that col1 is the column with the float value
the following computation will get rid of the leading zeroes
replace(ltrim(replace(char(decimal(col1,12,4)),'0',' ')),' ','0')
now you need to combine that with the previous solution of adding the minus sign :
select
      case
            when
                  wkz >= 0
            then
                  replace(ltrim(replace(char(decimal(wkz,12,4)),'0',' ')),' ','0')
            else  
                  '-' || replace(ltrim(replace(char(decimal(abs(wkz),12,4)),'0',' ')),' ','0')
         end

i tried it and it worked for me
hope this solves your problem

momi


0
 

Author Comment

by:davelane
ID: 18773367
It's dirty, but I like it :)
0

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