====================
Conversion Functions
====================

Presto will implicity convert numeric and character values to the
correct type if such a conversion is possible. Presto will not convert
between character and numeric types. For example, a query that expects
a varchar will not automatically convert a bigint value to an
equivalent varchar.

When necessary, values can be explicitly cast to a particular type.

Conversion Functions
--------------------

.. function:: cast(value AS type) -> type

    Explicitly cast a value as a type. This can be used to cast a
    varchar to a numeric value type and vice versa.

.. function:: try_cast(value AS type) -> type

    Like :func:`cast`, but returns null if the cast fails.

Miscellaneous
-------------

.. function:: typeof(expr) -> varchar

    Returns the name of the type of the provided expression::

        SELECT typeof(123); -- integer
        SELECT typeof('cat'); -- varchar(3)
        SELECT typeof(cos(2) + 1.5); -- double