What's the best way to write if/else if/else if/else in HIVE?

Question

Hive uses IF(condition, expression, expression), so when I want to do if / else if / else if / else, I have to do:

IF(a, 1, IF(b, 2, IF(c, 3, 4)))

Is there a better way to do this that's more readable?

Looking for something similar to the standard

if (a) {
  1
} else if (b) {
  2
} else if (c) {
  3
} else {
  4
}

YoungHobbit · Accepted Answer · 2018-02-19T18:03:14.503

48

You can use Hive Conditional CASE WHEN function for if-else scenario. The CASE Statement will provide you better readability with the same functionality.

CASE
  WHEN (condition1) THEN result1
  WHEN (condition2) THEN result2
  WHEN (condition3) THEN result3 
  WHEN (condition4) THEN result4
  ELSE result_default 
END AS attribute_name

edited Feb 19 '18 at 18:03

answered Sep 09 '15 at 07:08

YoungHobbit

13,254
9
50
73

2

cosmetic change needed, there is an extra ')' after the END – venkata Feb 19 '18 at 18:01

score 3 · Answer 2 · answered Nov 12 '19 at 16:17

You can easily achieve this using CASE WHEN statements.

CASE 
    WHEN a THEN 1
    WHEN b THEN 2
    WHEN c THEN 3
    ELSE 4
END AS attribute_name

For more information, refer official doc at https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF#LanguageManualUDF-ConditionalFunctions

score 0 · Answer 3 · answered Mar 16 '17 at 21:00

0

The best way to handle if else will be to write customize UDF for particular column.

answered Mar 16 '17 at 21:00

ronil

35
5

IDK how this would work? If we have functions already then better to use it. – ChikuMiku Jul 23 '17 at 04:41
1

I would compromise code readability to speed of execution. UDF typically crossed boundaries - out of hive to udf program. If possible in Hive try to accomplish it in Hive functions – viru Sep 29 '17 at 19:12

What's the best way to write if/else if/else if/else in HIVE?

3 Answers3

Linked