DB2 'SQL0901 SQL System Error.' when trying to SELECT from view containing UNION

Question

I am using a AS400 DB2 Database. In that Database I got 3 Views.

All Views have the exact same Columnnames and Datatypes. View 1 & 2 each consist of a Select Statement with aggregate Functions on the same source Table. Just the WHERE Conditions and the aggregate Functions are a little different.

View 3 simply is a UNION SELECT on both VIEW 1 & 2 merging the results.

So here is my Question.

SELECT 2 AS CLIENT, COLUMN1, COLUMN2, COLUMN3, COLUMN4, VALUE 
FROM SOME_DATABASE.VIEW3
WHERE COLUMN1 = @COLUMN1 AND COLUMN2 = @COLUMN2 ORDER BY COLUMN3

I can execute parameterized SELECT Statements (like the one above) from my c# Program on VIEW 1 & 2 without problems, but when i try to use a parameterized SELECT on VIEW 3 I get a 'SQL0901 SQL System Error.' However, when i dont use Parameters it just works fine.

Can anyone explain this behaviour to me?

AS400 DB2 Version is v5r2m0 The program is written in c# on .NET 4.0 in VS 2012 using 'IBM.Data.DB2.iSeries.dll' for accessing the Database

Definition View 1:

SELECT  COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4,  
        SUM(CAST((TRIM(SUBSTR(COLUMN5,104,1))||TRIM(SUBSTR(COLUMN5,94,3))||TRIM(SUBSTR(COLUMN5,98,3))||'.'||TRIM(SUBSTR(COLUMN5,102,2))) AS DECIMAL(10,2))) AS VALUE
FROM    SOME_DATABASE.SOME_TABLE  
WHERE   TRIM(SUBSTR(COLUMN5,105,3)) <> ''
AND     SUBSTR(COLUMN5,103,5) <> '  EUR'  
AND     COLUMN4 IN ('  $NEHHZ','$NEHHZVE','$NEHWMVE','  $NEHWW','$NEHWWVE','$NEHWWSK',' $NEHKW1',' $NEHKW2',' $NEHSK1',' $NEHSK2','  $NEHNV',' $NEHKZ1',' $NEHLZ1',' $NEHSZ1')  
GROUP BY  COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4  

Definition View 2:

SELECT  COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4,  
        SUM(CAST(TRIM(SUBSTR(COLUMN5,109,1))||TRANSLATE(TRIM(SUBSTR(COLUMN5,99,10)),'.',',') AS DECIMAL(10,2))) AS VALUE  
FROM    SOME_DATABASE.SOME_TABLE  
WHERE   COLUMN6 != 0  
AND     COLUMN4 IN (' SUM$HKV',' SUM$KWZ',' SUM$KZ',' SUM$LZ',' SUM$SZ',' SUM$WMZ',' SUM$WWZ')  
GROUP BY COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4  

Definition View 3:

SELECT COLUMN1, COLUMN2, COLUMN3, COLUMN4, VALUE
FROM SOME_DATABASE.VIEW1
UNION
SELECT COLUMN1, COLUMN2, COLUMN3, COLUMN4, VALUE
FROM SOME_DATABASE.VIEW2

Answer 1

It looks like parameterized SELECT Statements are not supported with views on views. I just replaced the 3rd View with a statement containing the definition of view 1 UNION view 2 like:

SELECT  COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4,  
        SUM(CAST((TRIM(SUBSTR(COLUMN5,104,1))||TRIM(SUBSTR(COLUMN5,94,3))||TRIM(SUBSTR(COLUMN5,98,3))||'.'||TRIM(SUBSTR(COLUMN5,102,2))) AS DECIMAL(10,2))) AS VALUE
FROM    SOME_DATABASE.SOME_TABLE  
WHERE   TRIM(SUBSTR(COLUMN5,105,3)) <> ''
AND     SUBSTR(COLUMN5,103,5) <> '  EUR'  
AND     COLUMN4 IN ('  $NEHHZ','$NEHHZVE','$NEHWMVE','  $NEHWW','$NEHWWVE','$NEHWWSK',' $NEHKW1',' $NEHKW2',' $NEHSK1',' $NEHSK2','  $NEHNV',' $NEHKZ1',' $NEHLZ1',' $NEHSZ1')  
GROUP BY  COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4

UNION

SELECT  COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4,  
        SUM(CAST(TRIM(SUBSTR(COLUMN5,109,1))||TRANSLATE(TRIM(SUBSTR(COLUMN5,99,10)),'.',',') AS DECIMAL(10,2))) AS VALUE  
FROM    SOME_DATABASE.SOME_TABLE  
WHERE   COLUMN6 != 0  
AND     COLUMN4 IN (' SUM$HKV',' SUM$KWZ',' SUM$KZ',' SUM$LZ',' SUM$SZ',' SUM$WMZ',' SUM$WWZ')  
GROUP BY COLUMN1,  
        COLUMN2,  
        COLUMN3,  
        COLUMN4 

And now it just works perfectly. But i still dont understand why this error occured.