Tuple(t1, T2, …)
Tuples are used for temporary column grouping. Columns can be grouped when an IN expression is used in a query, and for specifying certain formal parameters of lambda functions. For more information, see the sections and Higher order functions.
You can use a function to create a tuple:
Working with Data Types
When creating a tuple on the fly, ClickHouse automatically detects the type of each argument as the minimum of the types which can store the argument value. If the argument is , the type of the tuple element is Nullable.