This is little loose question
. The way, you post it - question makes no or very less sense.
If the question was,
I've a db2 table and "Select" is performed for row.
If sqlcode = 0 then values from row are used.
If sqlcode = +100, then program populates values.
so which select will return from db2 quicker, the sqlcode 0 with data or +100 without any data?
Answer could be - If the column is defined with null and you use IFNULL/VALUE/COALSCE on the column and retrieve the default value with sql code - which is eventually always zero.