RE: Insert of null-values with RPG, SQL or DFU

<SNIP>
>One thing that you must realize is that NULL is not a value - it is an
>attribute.  A column can have a value of 1.00 and also an attribute of
NULL.
>SQL "masks" this by not displaying the value if NULL is set.  We're forced
>so either use the null map or %nullind for each field.
>
>>nnoying, isn't it?

>Buck Calabro

Buck

Are you sure about the SQL comment?  If I have the following SQL statement

D    SalesNull S    4B 0
C/Exec SQL
C+             Select CustId,
C+                  CustNam,
C+                  CustSales
C+             Into:     DSCustId,
C+                  :DSCustName,
C+                  :DSCustSales:SalesNull   (-1=Null)
C+             From Customer  Where      CustId  =  'ACME'
C/End-Exec

I believe the value of the column DSCustSales is still what ever value you
left it at(ie 1.00 in your comment) even though the Indicator Variable
SalesNull will have a -1 denoting it is NULL.

It isn't a case of "SQL "masks" this by not displaying the value if NULL is
set"

SQL says  "If it is Null Capable,  Test the Indicator Variable associated
with the column and don't inspect/trust/use the Column itself if the flag
is -1 (ie Null)  ".

In SQL if I want to write a column as null,  I would manipulate the
associated Indicator Variable (the 4 byte binary) to a value of -1 for the
particular column I wanted Null.   You don't set the column itself to a
"NULL" value.  As you correctly said,  the Null state is an attribute of a
column NOT a value of the column.

RPG behaves the same way.  You set the Attribute (ie Null flag for the
column) not the field itself to some value.

John Carr



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