15.4. 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
-
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.
-
try_cast
(value AS type) → type Like
cast()
, but returns null if the cast fails.
Miscellaneous
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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