select req,
SUM(case when (stage='Selected') then count else NULL end) as Selected,
SUM(case when (stage='Initial Selection') then count else NULL end) as "Initial Selection",
SUM(case when (stage='Hr Round') then count else NULL end) as "Hr Round"
from table1 Group by req

In the above psql query stage is passed statically(hard coded) in CASE statement , How can we pass stage name dynamically from stage_table ?