COALESCE
COALESCE function is most similar to CASE expression as we define the cases while using CASE expression and each case is compared one by one similarly COALESCE compared each value one by one and if it found the first value = NULL then, the function also returns NULL value. COALESCE is a function that returns the first non-null expression in the lit. It can take more than two arguments.
Syntax:
COALESCE (expr1, expr2, expr3,...........exprn)