Hive function encyclopedia

1 Math functions

ceil round up the integer 
floor round down the integer 
abs absolute value function 
bin binary function 
hex hexadecimal function 
bround (DOUBLE a, INT d) banker's rounding method, retain d decimal place 
rand () random value 
round () retain d 
decimal

2.Date function

from_unixtime Convert timestamp to date 
unix_timestamp Get timestamp 
current_date Current date 
to_date Convert date 
datediff(string enddate, string startdate) Return the end date minus the number of days from the start date Return the number of days 
year Get the year 
date_format(current_date(),'MM.dd') Press Specify the format to return the date, such as: date_format("2016-06-22", "MM-dd")=06-22

3. Conditional function

if (>,1,2) 
case (>,when 1 then 2) 
isnull returns boolean 
isnotnull returns boolean 
nvl (null,1) ===1

4.Character functions

regexp_extract regular expression parsing function 
regexp_replace('hello,world','o|l','e'); regular expression replacement 
substr, substring string interception 
reverse string flip function 
trim remove spaces 
split string split function 
instr( xx,x) returns a number without returning 0

5. Aggregation function

max maximum value 
min minimum value 
count number 
sum sum 
avg average

6. Table generation function

explode(ARRAY) Each row corresponds to an element in the array

7. Type conversion function

cast(expr as) Convert expr to type type such as: cast("1" as BIGINT) Convert string 1 to BIGINT type. If the conversion fails, NULL binary will be returned. Convert to 
binary

8. Aggregate functions

size(Array) Gets the number of sets 
map_keys(Map<KV>) Returns all keys in the map 
array_contains(Array, value) Returns true if the array Array contains value. Otherwise return false 
sort_array(Array) sorting function