Progress/400
Product Guide


How Progress/400 Handles SQL NULL and Legacy Unknown Value Support

Progress queries and SQL queries on the AS/400 can return different values. As a comparison, Table B–4 shows the return values for queries based on your DUPPRODB and NULL capable selections.

Table B–4: SQL and 4GL Query Results with NULL Capable and ALWPROUNK Settings  
Progress/400 Data Dictionary NULL Capable


SQL Query Result


4GL Query Result
YES
NULL
Returns unknown value (?)
NO
Legacy unknown value
Returns unknown value (?)
NO
N/A
OS/400 data mapping error


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