CAST Function in Apache Hive

The Apache Hive CAST function is a type conversion function that converts data types from one to another. It can convert a string to an integer, an integer to a decimal, a string to a date, and a date to a timestamp, among other things.

For a better understanding, look at the examples below.

Test Data:
SELECT * FROM testdate;
Result: 
Date1             Date2
2021-07-08    2021-07-08 02:49:00

SELECT CAST(date2 AS date) from testdate;
Result: 2021-07-08
The above statement converted the timestamp value into date format.

SELECT CAST(‘2016-10-20’ AS Date);
Result: 2016-10-20
The above statement converted the string value into date format.

SELECT CAST(date2 AS BIGINT) FROM testdate;
Result: 1625737740
The above statement converted the timestamp value into integral representation i.e. BIGINT data type.

SELECT FROM_UNIXTIME(1625737740);
Result: 2021-07-08 02:49:00
The above statement converted the timestamp value which is in an integral representation back into date format.

SELECT TO_DATE(FROM_UNIXTIME(1625737740));
Result: 2021-07-08
The above statement converted the timestamp value which is in an integral representation into a simple date format.

SELECT CAST(1 AS FLOAT);
Result: 1.0
The above statement converted the integral value into decimal format.

SELECT CAST(1.99 AS INT);
Result: 1
The above statement converted the decimal value into integral representation.

SELECT CAST(date1 AS timestamp) from testdate;
Result: 2021-07-08 00:00:00
The above statement converted the date value into timestamp format.

SELECT CAST(‘1.99’ AS float);
Result: 1.99
The above statement converted the string value into decimal format.

SELECT CAST(‘1.99’ AS int);
Result: 1
The above statement converted the string value into integral representation.



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