The General function are use in SQL
1-NVL (exp1,exp2)
2-NVL2 (exp1,exp2,exp3)
3-NULLIF (exp1,exp2)
4-COALESCE (exp1,exp2,exp3,......,expn)
For example:
"sql SELECT last_name...
Aggregate Functions:
AVG() - Returns the average value
COUNT() - Returns the number of rows
FIRST() - Returns the first value
LAST() - Returns the last value
MAX() - Returns the largest...