Db2 sql query modified version query

hi guys,

my requirement has changed a little so i am putting it in a new post...

first requirement

SELECT * FROM tab1 a,tab2 b WHERE
a.ID='b.col1+b.col2'

i want to append two columns data to form a where clause of the query..

i am trying to put it in DB2..but not successfull..any help


second requirment

my first query gives me the output as colA, colB
select colA,colB from tab1 where colC='XXX'

no my second query i write to get the value of colA,colB
select * from tab2 where col1=colA
select * from tab2 where col1=colB
NOW I WANT TO DO THIS FROM A SINGLE QUERY

Hi Anaik

Your first requirement seems like a concatenation.
The way to code that in DB2 is:
assuming that all 3 columns are of a string/character-type.
If that assumption is incorrect, you have to convert the numeric
columns to characters using the function CHAR(), e.g.:
when col1 is of a numeric type.

Now regarding your second requirement: I assume there is an
OR-relation between the SELECTS on tab2. I suggest either a subselect:
or a join:

Your choice may depend on the importance of:

• maintenance (and thus clarity of the whole query, in this case I would favour the subselect)
• performance (where the join may have an advantage, as the optimizer will easier conclude
  that one pass through tab1 will suffice)

The only difference between both these and your original is the fact that your original queries
may yield some duplicate values in cases where colA and colB have the same value within the same row.
The OR in both my queries will reduce the two resultvalues to one row, whereas your example will produce
that resultvalue in both the queries on tab2, and you would end up with more resulting rows.
If that really is a problem please let me know.

Regards, Jaap.
19'3/112