Common oracle Functions

Whether you are a "development engineer" or "implementation engineer", there may be many online design report requirements in the company's related systems. Before you design a report, first, we need to understand how to write SQL statements, functions, processes, and Data Objects of specific databases. The following describes some common functions of oracle databases.

Whether you are a "development engineer" or "implementation engineer", there may be many online design report requirements in the company's related systems. Before you design a report, first, we need to understand how to write SQL statements, functions, processes, and Data Objects of specific databases. The following describes some common functions of oracle databases.

Whether you are a "development engineer" or "implementation engineer", there may be many online design report requirements in the company's related systems. Before you design a report, first, we must understand how to write SQL statements, functions, processes, and Data Objects of specific databases. Below we will briefly introduce some common functions of oracle databases, hope to help some beginners:

Single-record functions in SQL
1. ASCII
Returns the decimal number corresponding to the specified character;
SQL> select ascii ('A') A, ascii ('A') A, ascii ('0') zero, ascii ('') space from dual;

A ZERO SPACE
------------------------------------
65 97 48 32

2. CHR
Returns the corresponding characters;
SQL> select chr (54740) zhao, chr (65) chr65 from dual;

ZH C
---
Zhao

3. CONCAT
Connect two strings;
SQL> select concat ('010-', '000000') |' to 23' Gao Qian competing phone number from dual;

Gao Qian's phone number
----------------
010-88888888 to 23

4. INITCAP
Returns a string and converts the first letter of the string to uppercase;
SQL> select initcap ('Smith ') upp from dual;

UPP
-----
Smith

5. INSTR (C1, C2, I, J)
Searches for a specified character in a string and returns the location where the specified character is found;
String searched by C1
String to be searched by C2
The start position of the I search. The default value is 1.
Where J appears. The default value is 1.
SQL> select instr ('oracle traning', 'A', 1, 2) instring from dual;

INSTRING
---------
9

6. LENGTH
Returns the length of the string;
SQL> select name, length (name), addr, length (addr), sal, length (to_char (sal) from gao. nchar_tst;

Name length (NAME) addr length (ADDR) sal length (TO_CHAR (SAL ))
---------------------------------------------------------------------------
Gao Qian Jing 3 Beijing haiding District 6 9999.99 7

7. LOWER
Returns a string and lowercase letters of all characters.
SQL> select lower ('abbccdd') AaBbCcDd from dual;

AABBCCDD
--------
Aabbccdd

8. UPPER
Returns a string and upper-case all characters.
SQL> select upper ('abbccdd') upper from dual;

UPPER
--------
AABBCCDD

9. RPAD and LPAD (paste characters)
Pad the character on the right of the column
LPAD paste characters on the left of the column
SQL> select lpad (rpad ('gao', 10, '*'), 17, '*') from dual;

LPAD (RPAD ('gao', 1
-----------------
* ******* Gao *******
If the character is not enough, use * to fill it up.

10. LTRIM and RTRIM
LTRIM deletes the string on the left
RTRIM deletes the string that appears on the right.
SQL> select ltrim (rtrim ('gao qian jing', ''),'') from dual;

LTRIM (RTRIM ('
-------------
Gao qian jing

11. SUBSTR (string, start, count)
Substring, starting from start, count
SQL> select substr ('123', 13088888888) from dual;

SUBSTR ('
--------
08888888

12. REPLACE ('string', 's1', 's2 ')
String: the character or variable to be replaced.
String to be replaced by s1
String to be replaced by s2
SQL> select replace ('He love you', 'hes', 'I') from dual;

REPLACE ('H
----------
I love you

13. SOUNDEX
Returns a string with the same pronunciation as a given string.
SQL> create table table1 (xm varchar (8 ));
SQL> insert into table1 values ('weate ');
SQL> insert into table1 values ('wether ');
SQL> insert into table1 values ('gao ');

SQL> select xm from table1 where soundex (xm) = soundex ('weate ');

XM
--------
Weather
Wether

14. TRIM ('s 'from 'string ')
LEADING
TRAILING
If this parameter is not specified, the space character is used by default.

15. ABS
Returns the absolute value of a specified value.
SQL> select abs (100), abs (-100) from dual;

ABS (100) ABS (-100)
------------------
100 100

16. ACOS
Returns the arc cosine value.
SQL> select acos (-1) from dual;

ACOS (-1)
---------
3.1415927

17. ASIN
Returns the arcsin value.
SQL & gt; select asin (0.5) from dual;

ASIN (0.5)
---------
. 52359878

18. ATAN
Returns the arc tangent of a number.
SQL> select atan (1) from dual;

ATAN (1)
---------
. 78539816

19. CEIL
Returns the smallest integer greater than or equal to the given number.
SQL> select ceil (3.1415927) from dual;

CEIL (3.1415927)
---------------
4

20. COS
Returns the cosine of a given number.
SQL> select cos (-3.1415927) from dual;

COS (-1, 3.1415927)
---------------
-1

21. COSH
Returns the arc cosine of a number.
SQL> select cosh (20) from dual;

COSH (20)
---------
242582598

22. EXP
Returns the n root of the number e.
SQL> select exp (2), exp (1) from dual;

EXP (2) EXP (1)
------------------
7.3890561 2.7182818

23. FLOOR
Returns an integer to a given number.
SQL> select floor (2345.67) from dual;

FLOOR (2345.67)
--------------
2345

24. LN
Returns the logarithm of a number.
SQL> select ln (1), ln (2), ln (2.7182818) from dual;

LN (1) LN (2) LN (1, 2.7182818)
-------------------------------
0. 69314718. 99999999

25. LOG (n1, n2)
Returns the base n2 logarithm of n1.
SQL> select log (2, 1), log (2, 4) from dual;

LOG (2, 1) LOG (2, 4)
------------------
0 2

26. MOD (n1, n2)
Returns the remainder of n1 divided by n2.
SQL> select mod (10, 3), mod (3, 3), mod (2, 3) from dual;

MOD)
---------------------------
1 0 2

27. POWER
Returns the n2 root of n1.
SQL> select power (2, 10), power (3, 3) from dual;

POWER (2, 10) POWER (3, 3)
---------------------
1024 27

29. SIGN
Returns 1 if the number n is greater than 0,-1 if the value is less than 0, and 0 if the value is 0.
SQL> select sign (123), sign (-100), sign (0) from dual;

SIGN (123) SIGN (-100) SIGN (0)
----------------------------
1-1 0

30. SIN
Returns the sine of a number.
SQL> select sin (1.57079) from dual;

SIN (1.57079)
------------
1

31. SIGH
Returns the hyperbolic sine value.
SQL> select sin (20), sinh (20) from dual;

SIN (20) SINH (20)
------------------
.. 91294525 242582598

32. SQRT
Returns the root of number n.
SQL> select sqrt (64), sqrt (10) from dual;

SQRT (64) SQRT (10)
------------------
8 3.1622777

33. TAN
Returns the tangent of a number.
SQL> select tan (20), tan (10) from dual;

TAN (20) TAN (10)
------------------
2.2371609. 64836083

34. TANH
Returns the hyperbolic tangent of number n.
SQL> select tanh (20), tan (20) from dual;

TANH (20) TAN (20)
------------------
1 2.2371609

28. ROUND and TRUNC
Round according to the specified precision
SQL> select round (55.5), round (-55.4), trunc (55.5), trunc (-55.5) from dual;

ROUND (55.5) ROUND (-55.4) TRUNC (55.5) TRUNC (-55.5)
----------------------------------------------
56-55 55-55
35. TRUNC
Truncate a number based on the specified precision
SQL> select trunc (124.1666,-2) trunc1, trunc (124.16666, 2) from dual;

TRUNC1 TRUNC (124.16666, 2)
---------------------------
100 124.16

36. ADD_MONTHS
Add or subtract a month
SQL> select to_char (add_months (to_date ('000000', 'yyymmm'), 2), 'yyymmm') from dual;

TO_CHA
------
200002
SQL> select to_char (add_months (to_date ('000000', 'yyymmm'),-2), 'yyymmm') from dual;

TO_CHA
------
199910

37. LAST_DAY
Returns the last day of the date.
SQL> select to_char (sysdate, 'yyyy. mm. dd'), to_char (sysdate) + 1, 'yyyy. mm. dd') from dual;

TO_CHAR (SY TO_CHAR (S
--------------------
2004.05.09 2004.05.10
SQL> select last_day (sysdate) from dual;

LAST_DAY (S
----------
September 31-04

38. MONTHS_BETWEEN (date2, date1)
Given the month of the date2-date1
SQL> select months_between ('19-December-1999 ', '19-March-1999') mon_between from dual;

MON_BETWEEN
-----------
9
SQL> selectmonths_between (to_date ('2017. 05.20 ', 'yyyy. mm. dd'), to_date ('2017. 05.20 ', 'yyyy. mm. dd') mon_betw from dual;

MON_BETW
---------
-60

39. NEW_TIME (date, 'this', 'that ')
Returns the date and time in this time zone = other time zone.
SQL> select to_char (sysdate, 'yyyy. mm. dd hh24: mi: ss') bj_time, to_char (new_time
2 (sysdate, 'pdt ', 'gmt'), 'yyyy. mm. dd hh24: mi: ss') los_angles from dual;

BJ_TIME LOS_ANGLES
--------------------------------------
2004.05.09 11:05:32 2004.05.09 18:05:32

40. NEXT_DAY (date, 'day ')
Returns the date of the week and the date of the next week after week x.
SQL> select next_day ('18-May-2001 ', 'Friday') next_day from dual;

NEXT_DAY
----------
25-5-01

41. SYSDATE
Used to obtain the current date of the system
SQL> select to_char (sysdate, 'dd-mm-yyyy Day') from dual;

TO_CHAR (SYSDATE ,'
-----------------
09-05-2004 Sunday
Trunc (date, fmt) truncates the date according to the given requirements. If fmt = 'mi ', it indicates that the minute is retained and the second is truncated.
SQL> select to_char (trunc (sysdate, 'hh'), 'yyyy. mm. dd hh24: mi: ss') hh,
2 to_char (trunc (sysdate, 'mi'), 'yyyy. mm. dd hh24: mi: ss') hhmm from dual;

HH HHMM
--------------------------------------
2004.05.09 11:00:00 2004.05.09 11:17:00

42. CHARTOROWID
Convert character data type to ROWID type
SQL> select rowid, rowidtochar (rowid), ename from scott. emp;

Rowid rowidtochar (ROWID) ENAME
----------------------------------------------
AAAAfKAACAAAAEqAAA SMITH
AAAAfKAACAAAAEqAAB ALLEN
AAAAfKAACAAAAEqAAC WARD
AAAAfKAACAAAAEqAAD JONES

43. CONVERT (c, dset, sset)
Convert the source string sset from one language character set to another destination dset Character Set
SQL> select convert ('strutz', 'we8hp ', 'f7dec') "conversion" from dual;

Conver
------
Strutz

44. HEXTORAW
Converts a hexadecimal string to a binary string.

45. RAWTOHEXT
Converts a binary string to a hexadecimal string.

46. ROWIDTOCHAR
Convert the ROWID data type to the character type

47. TO_CHAR (date, 'format ')
SQL> select to_char (sysdate, 'yyyy/mm/dd hh24: mi: ss') from dual;

TO_CHAR (SYSDATE, 'yy
-------------------
2004/05/09 21:14:41

48. TO_DATE (string, 'format ')
Converts a string to a date in ORACLE.

49. TO_MULTI_BYTE
Converts a single-byte character in a string to a multi-byte character.
SQL> select to_multi_byte ('high') from dual;

TO
--
High

50. TO_NUMBER
Converts a given character to a number.
SQL> select to_number ('20140901') year from dual;

YEAR
---------
1999

51. BFILENAME (dir, file)
Specify an external binary file
SQL> insert into file_tb1 values(bfilename('lob_dir1', 'image1.gif '));

52. CONVERT ('x', 'desc', 'source ')
Convert the source of the x field or variable to desc
SQL> select sid, serial #, username, decode (command,
2 0, 'none ',
3 2, 'insert ',
4 3,
5 'select ',
6 6, 'update ',
7, 'delete ',
8 8, 'drop ',
9 'other') cmd from v $ session where type! = 'Background ';

Sid serial # USERNAME CMD
------------------------------------------------------
1 1 none
2 1 none
3 1 none
4 1 none
5 1 none
6 1 none
7 1275 none
8 1275 none
9 20 GAO select
10 40 GAO none

53. DUMP (s, fmt, start, length)
The DUMP function returns a VARCHAR2 value in the internal numeric format specified by fmt.
SQL> col global_name for a30
SQL> col dump_string for a50
SQL & gt; set lin 200
SQL> select global_name, dump (global_name, 1017,8, 5) dump_string from global_name;

GLOBAL_NAME DUMP_STRING
--------------------------------------------------------------------------------
ORACLE. WORLD Typ = 1 Len = 12 CharacterSet = ZHS16GBK: W, O, R, L, D

54. EMPTY_BLOB () and EMPTY_CLOB ()
Both functions are used to initialize fields of the big data type.

55. GREATEST
Returns the maximum value in a group of expressions, that is, compare the encoding size of characters.
SQL> select greatest ('A', 'AB', 'ac') from dual;

GR
--
AC
SQL> select greatest ('Ah', 'an', 'day') from dual;

GR
--
Days

56. LEAST
Returns the minimum value in a group of expressions.
SQL> select least ('Ah', 'an', 'day') from dual;

LE
--
Ah

57. UID
Returns a unique integer that identifies the current user.
SQL> show user
The USER is "GAO"
SQL> select username, user_id from dba_users where user_id = uid;

USERNAME USER_ID
---------------------------------------
GAO 25

58. USER
Returns the name of the current user.
SQL> select user from dual;

USER
------------------------------
GAO

59. USEREVN
Returns information about the current user environment. The opt can be:
ENTRYID, SESSIONID, TERMINAL, ISDBA, LABLE, LANGUAGE, CLIENT_INFO, LANG, VSIZE
ISDBA checks whether the current user is a DBA. If yes, true is returned.
SQL> select userenv ('isdba ') from dual;

USEREN
------
FALSE
SQL> select userenv ('isdba ') from dual;

USEREN
------
TRUE
SESSION
Returned session flag
SQL> select userenv ('sessionid') from dual;

USERENV ('sessionid ')
--------------------
152
ENTRYID
Return session Population Sign
SQL> select userenv ('entryid') from dual;

USERENV ('entryid ')
------------------
0
INSTANCE
Returns the flag of the current INSTANCE.
SQL> select userenv ('instance') from dual;

USERENV ('instance ')
-------------------
1
LANGUAGE
Returns the current environment variable.
SQL> select userenv ('language') from dual;

USERENV ('language ')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
Returns the abbreviation of the current environment language.
SQL> select userenv ('lang ') from dual;

USERENV ('lang ')
----------------------------------------------------
ZHS
TERMINAL
Returns the identifier of the user's terminal or machine.
SQL> select userenv ('terminal') from dual;

USERENV ('termina
----------------
GAO
VSIZE (X)
Returns the size (in bytes) of X.
SQL> select vsize (user), user from dual;

VSIZE (USER) USER
-----------------------------------------
6 SYSTEM

60. AVG (DISTINCT | ALL)
All indicates the average value for all values, while distinct only calculates the average value for different values.
SQLWKS> create table table3 (xm varchar (8), sal number (7,2 ));
The statement has been processed.
SQLWKS> insert into table3 values ('gao', 1111.11 );
SQLWKS> insert into table3 values ('gao', 1111.11 );
SQLWKS> insert into table3 values ('zhu', 5555.55 );
SQLWKS> commit;

SQL> select avg (distinct sal) from gao. table3;

AVG (DISTINCTSAL)
----------------
3333.33

SQL> select avg (all sal) from gao. table3;

AVG (ALLSAL)
-----------
2592.59

61. MAX (DISTINCT | ALL)
For maximum value, "ALL" indicates the maximum value for ALL values, and "DISTINCT" indicates the maximum value for different values. For the same value, only one time is used.
SQL> select max (distinct sal) from scott. emp;

MAX (DISTINCTSAL)
----------------
5000

62. MIN (DISTINCT | ALL)
Minimum value. "ALL" indicates minimum value for ALL values, and "DISTINCT" indicates minimum value for different values. The same value is used only once.
SQL> select min (all sal) from gao. table3;

MIN (ALLSAL)
-----------
1111.11

63. STDDEV (distinct | all)
Evaluate standard deviation. "ALL" indicates evaluate standard deviation for ALL values, and "DISTINCT" indicates evaluate standard deviation for different values only.
SQL> select stddev (sal) from scott. emp;

STDDEV (SAL)
-----------
1182.5032

SQL> select stddev (distinct sal) from scott. emp;

STDDEV (DISTINCTSAL)
-------------------
1229.951

64. VARIANCE (DISTINCT | ALL)
Covariance

SQL> select variance (sal) from scott. emp;

VARIANCE (SAL)
-------------
1398313.9

65. GROUP
It is mainly used to calculate the number of a group.
SQL> select deptno, count (*), sum (sal) from scott. emp group by deptno;

Deptno count (*) SUM (SAL)
---------------------------
10 3 8750
20 5 10875
30 6 9400

66. HAVING
Grouping statistics plus restrictions
SQL> select deptno, count (*), sum (sal) from scott. emp group by deptno having count (*)> = 5;

Deptno count (*) SUM (SAL)
---------------------------
20 5 10875
30 6 9400
SQL> select deptno, count (*), sum (sal) from scott. emp having count (*)> = 5 group by deptno;

Deptno count (*) SUM (SAL)
---------------------------
20 5 10875
30 6 9400

67. ORDER
Used to sort and output the queried results.
SQL> select deptno, ename, sal from scott. emp order by deptno, sal desc;

DEPTNO ENAME SAL
----------------------------
10 KING 5000
10 CLARK 2450
10 MILLER 1300
20 SCOTT 3000
20 FORD 3000
20 JONES 2975
20 ADAMS 1100
20 SMITH 800
30 BLAKE 2850
30 ALLEN 1600
30 TURNER 1500
30 WARD 1250
30 MARTIN 1250
30 JAMES 950

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