max aggregate function
Applies to: 
Databricks SQL Databricks Runtime
Returns the maximum value of expr in a group.
Syntax
max(expr) [FILTER ( WHERE cond ) ]
This function can also be invoked as a window function using the OVER clause.
Arguments
expr: An expression of any type that can be ordered.cond: An optional boolean expression filtering the rows used for aggregation.
Returns
The result type matches the type of the argument.
Examples
> SELECT max(col) FROM VALUES (10), (50), (20) AS tab(col);
50