map_concat function
Applies to: 
Databricks SQL Databricks Runtime
Returns the union of all expr map expressions.
Syntax
map_concat([ expr1 [, ...] ])
Arguments
exprN: A MAP expression. AllexprNmust share a least common type.
Returns
A MAP of the least common type of exprN.
If no argument is provided, an empty map. If there is a key collision an error is raised.
Examples
SQL
> SELECT map_concat(map(1, 'a', 2, 'b'), map(3, 'c'));
{1 -> a, 2 -> b, 3 -> c}