Based on the links for DB2 LUW, the following should get you what you need.
avgcte as (SELECT AVG(exp1) as avgexp1, AVG(exp2) as avgexp2 FROM table1),
covarcte as (SELECT AVG((exp1 - avgexp1)*(exp2-avgexp2)) as covarvalue FROM
corrcte as (SELECT covarvalue/(STDDEV(exp1)*STDDEV(exp2)) as corrvalue FROM
SELECT * from avgcte, covarcte, corrcte
I can't test this out right now, but it looks like it might work to me.