1. String length function: length
Syntax: length(string A)
Return value: int
Description: Return the length of string A
Example:
hive> select length('abcedfg')
7
2. String reverse function: reverse
Syntax: reverse(string A)
Return value: string
Description: Return the reversed result of string A
Example:
hive> select reverse('abcedfg') ;
gfdecba
3. String concatenation function: concat
Syntax: concat(string A, string B…)
Return value: string
Description: Return the result of the concatenation of input strings, support any input string
Example:
hive> select concat('abc' ,'def','gh');
abcdefgh
4. String concatenation function with separator: concat_ws
Syntax: concat_ws(string SEP, string A, string B…)
Return value: string
Description: Return the result of the concatenation of the input strings, SEP represents the separator between each string
Example :
hive> select concat_ws('-','abc','def','gh') ;
abc-def-gh
5. String interception function: substr, substring
Syntax: substr(string A, int start), substring(string A, int start)
Return value: string
Description: Return the string from the start position to the end of string A
Example:
hive > select substr('abcdefghijklmnopqrst',3) ;
cdefghijklmnopqrst
hive> select substr('abcdefghijklmnopqrst',-3) ; (same as ORACLE)
rst
hive> select substring('abcdefghijklmnopqrst',3) ;
cdefghijklmnopqrst
hive> select substring(' abcdefghijklmnopqrst',-3) ; (same as ORACLE)
rst
6. String interception function: substr, substring
Syntax: substr(string A, int start, int len), substring(string A, int start, int len)
Return value: string
Description: The returned string A starts from the start position, An example of a string of length len
:
hive> select substr('abcdefghijklmnopqrst',3,9);
cdefghijk
hive> select substring('abcdefghijklmnopqrst',3,9);
cdefghijk
7. String to uppercase function: upper, ucase
Syntax: upper(string A) ucase(string A)
Return value: string
Description: Return the uppercase format of string A
Example:
hive> select upper('abSEd');
ABSED
hive > select ucase('abSEd');
ABSED
8. String to lowercase function: lower,lcase
Syntax: lower(string A) lcase(string A)
Return value: string
Description: Return the lowercase format of string A
Example:
hive> select lower('abSEd') from dual;
absed
hive> select lcase('abSEd') from dual;
absed
9. Remove spaces function: trim
syntax: trim(string A)
Return value: string
Description: Remove spaces on both sides of the string
Example:
hive> select trim(' abc ') from dual;
abc
10. Function to remove spaces on the left: ltrim
syntax: ltrim(string A)
Return value: string
Description: Remove spaces on the left side of the string
Example:
hive> select ltrim(' abc ') from dual;
abc
11. Function to remove spaces on the right: rtrim
syntax: rtrim(string A)
Return value: string
Description: Remove spaces on the right side of the string
Example:
hive> select rtrim(' abc ') from dual;
abc
12. Regular expression parsing function:
the index in regexp_extract is the position according to the regular string ( )
Syntax: regexp_extract(string subject, string pattern, int index)
Return value: string
Description: The string subject follows the pattern regular expression The rule split, returns the character specified by index. Note that in some cases escape characters are used
for example:
hive> select regexp_extract('foothebar', 'foo(.*?)(bar)', 1) from dual;
the
hive> select regexp_extract('foothebar', ' foo(.*?)(bar)', 2) from dual;
bar
hive> select regexp_extract('foothebar', 'foo(.*?)(bar)', 0) from dual;
foothebar
13. function parse_url, parsing URL string
parse_url(url, partToExtract[, key]) - extracts a part from a URL
parsed URL string, the options of partToExtract include [HOST,PATH,QUERY,REF,PROTOCOL,FILE,AUTHORITY,USERINFO].
Example:
String description: Parse the json string json_string and return the content specified by path. Returns NULL if the input json string is invalid. Example:
hive> select get_json_object(‘{“store”:
> {“fruit”:\[{"weight":8,"type":"apple"},{"weight":9,"type":"pear"}],
> “bicycle”:{“price”:19.95,”color”:”red”}
> },
> “email”:”amy@only_for_json_udf_test.net”,
> “owner”:”amy”
> }
> ‘,’$.owner’) from dual;
amy
使用实例：
select get_json_object('{"store":{"fruit":\["aa","bb","cc"]},"owner":"amy"}','$.store.fruit[0]') from test_msg limit 1;
15. Space string function: space
syntax: space(int n)
Return value: string
Description: Return a string of length n
Example:
hive> select space(10) from dual;
hive> select length(space(10)) from dual;
10
16. Repeat string function: repeat
Syntax: repeat(string str, int n)
Return value: string
Description: Return the str string repeated n times
Example:
hive> select repeat('abc',5) from dual;
abcabcabcabcabc
17. First character ascii function: ascii
syntax: ascii(string str)
Return value: int
Description: Return the ascii code of the first character of string str
Example:
hive> select ascii('abcde') from dual;
97
18. Left complement function: lpad
Syntax: lpad(string str, int len, string pad)
Return value: string
Description: Left complement str to len position with pad
Example:
hive> select lpad('abc',10, 'td') from dual;
tdtdtdtabc
19. Different from GP and ORACLE, pad cannot be
right-complemented by default. Function: rpad
syntax: rpad(string str, int len, string pad)
Return value: string
Description: Use pad to right-complement str to len.
Example:
hive> select rpad('abc',10,'td') from dual;
abctdtdtdt
20. Split string function: split
Syntax: split(string str, string pat)
Return value: array
Description: Split str according to the pat string, and the split string array will be returned
Example:
hive> select split('abtcdtef', 't') from dual;
["ab","cd","ef"]
21. Set search function: find_in_set
Syntax: find_in_set(string str, string strList)
Return value: int
Description: Return the position where str appears for the first time in strlist, which is a string separated by commas. If the str character is not found, it will return 0.
Example:
hive> select find_in_set('ab','ef,ab,de') from dual;
2
hive> select find_in_set('at','ef,ab,de') from dual;
0