DSXchange

Posted: **Sat Jan 03, 2009 8:23 am**

I have a select query on uvsh, which concatenates the different fields and replaces any @VM and @TM

select EVAL "CONVERT(@TM:@VM,'.', Field1:'-':Field2:'-':Field3) from H_TABLE;

This code works fine, when there aren't any nullables in the fields. When any of the fields is null, the output is null (offcourse thats the funcationality of convert function)

So I applied the above null check condition to each of the fields, if it is null, then the output is empty string else it is the same field.

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select EVAL "CONVERT(@TM:@VM,'.', If Isnull(Field1) then '' else Field1:'-':If Isnull(Field2) then '' else Field2:'-':If Isnull(Field3) then '' else Field3) from H_TABLE;

But, whenever Field2 is null, Field3 doesn't get displayed irrespective of whether it is null or not. I do get the output though i.e. only Field1 gets displayed with field seperators until Field2.

I tried different approach using @NULL.STR(below), but it doesn't work either.

Code: Select all

select EVAL "CONVERT(@TM:@VM,@NULL.STR,'.', Field1:'-':Field2:'-':Field3) from H_TABLE;

Posted: **Sat Jan 03, 2009 1:14 pm**

Think about it. NULL in any operation (including concatenation) must return NULL.

Now re-think what you want to get out of this expression and post that specification.

Posted: **Sat Jan 03, 2009 1:36 pm**

ray.wurlod wrote:Think about it. NULL in any operation (including concatenation) must return NULL.

Now re-think what you want to get out of this expression and post that specification.

Shouldn't the below code handle the situation, because null is being replaced with empty string.

Code: Select all

select EVAL "CONVERT(@TM:@VM,'.', If Isnull(Field1) then '' else Field1:'-':If Isnull(Field2) then '' else Field2:'-':If Isnull(Field3) then '' else Field3) from H_TABLE;

I wanted to get the output as

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Field1-Field2-Field3

When Field2 is null (Field1 and Field3 are not nulls). I am expecting,

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Field1--Field3

But I get

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Field1-

Posted: **Sun Jan 04, 2009 3:55 pm**

Probably. For testing purposes can you output three extra columns that contain "Y" if the field is null and "N" otherwise to see what's consistent?

Not sure what your CONVERT is trying to achieve, perhaps leave that out of the mix also, or convert all mark characters to "printables", for example

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Convert(@FM:@VM:@SM:@TM,'~}|{',expression)

just to see what's actually happening in expression.

DSXchange

select query on uvsh, involving nulls

select query on uvsh, involving nulls