Coalesce is a SQL function used for handling NULL values. It returns the first non-null expression from the list. Each expression is evaluated for being NULL or not and the first non-null expression will be returned as the output. It takes at least two arguments in the list.
COALESCE(expr 1,expr 2,....,expr n)
expr1, expr,2, expr n represents the values in the list.
Select Coalesce(Null,'Hello', Null, 'World',Null)