How to generate a GUID in Oracle?

问题

Is it possible to auto-generate a GUID into an Insert statement?

Also, what type of field should I use to store this GUID?

回答1:

You can use the SYS_GUID() function to generate a GUID in your insert statement:

insert into mytable (guid_col, data) values (sys_guid(), 'xxx');

The preferred datatype for storing GUIDs is RAW(16).

As Gopinath answer:

 select sys_guid() from dual
 union all
 select sys_guid() from dual
 union all 
 select sys_guid() from dual

You get

88FDC68C75DDF955E040449808B55601
88FDC68C75DEF955E040449808B55601
88FDC68C75DFF955E040449808B55601

As Tony Andrews says, differs only at one character

88FDC68C75DDF955E040449808B55601
88FDC68C75DEF955E040449808B55601
88FDC68C75DFF955E040449808B55601

Maybe useful: http://feuerthoughts.blogspot.com/2006/02/watch-out-for-sequential-oracle-guids.html

回答2:

You can also include the guid in the create statement of the table as default, for example:

create table t_sysguid
( id     raw(16) default sys_guid() primary key
, filler varchar2(1000)
)
/

See here: http://rwijk.blogspot.com/2009/12/sysguid.html

回答3:

It is not clear what you mean by auto-generate a guid into an insert statement but at a guess, I think you are trying to do something like the following:

INSERT INTO MY_TAB (ID, NAME) VALUES (SYS_GUID(), 'Adams');
INSERT INTO MY_TAB (ID, NAME) VALUES (SYS_GUID(), 'Baker');

In that case I believe the ID column should be declared as RAW(16);

I am doing this off the top of my head. I don't have an Oracle instance handy to test against, but I think that is what you want.

回答4:

sys_guid() is a poor option, as other answers have mentioned. One way to generate UUIDs and avoid sequential values is to generate random hex strings yourself:

select regexp_replace(
    to_char(
        DBMS_RANDOM.value(0, power(2, 128)-1),
        'FM0xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'),
    '([a-f0-9]{8})([a-f0-9]{4})([a-f0-9]{4})([a-f0-9]{4})([a-f0-9]{12})',
    '\1-\2-\3-\4-\5') from DUAL;

回答5:

Example found on: http://www.orafaq.com/usenet/comp.databases.oracle.server/2006/12/20/0646.htm

SELECT REGEXP_REPLACE(SYS_GUID(), '(.{8})(.{4})(.{4})(.{4})(.{12})', '\1-\2-\3-\4-\5') MSSQL_GUID  FROM DUAL

Result:

6C7C9A50-3514-4E77-E053-B30210AC1082

回答6:

You can run the following query

 select sys_guid() from dual
 union all
 select sys_guid() from dual
 union all 
 select sys_guid() from dual

回答7:

you can use function bellow in order to generate your UUID

create or replace FUNCTION RANDOM_GUID
    RETURN VARCHAR2 IS

    RNG    NUMBER;
    N      BINARY_INTEGER;
    CCS    VARCHAR2 (128);
    XSTR   VARCHAR2 (4000) := NULL;
  BEGIN
    CCS := '0123456789' || 'ABCDEF';
    RNG := 15;

    FOR I IN 1 .. 32 LOOP
      N := TRUNC (RNG * DBMS_RANDOM.VALUE) + 1;
      XSTR := XSTR || SUBSTR (CCS, N, 1);
    END LOOP;

    RETURN SUBSTR(XSTR, 1, 4) || '-' ||
        SUBSTR(XSTR, 5, 4)        || '-' ||
        SUBSTR(XSTR, 9, 4)        || '-' ||
        SUBSTR(XSTR, 13,4)        || '-' ||
        SUBSTR(XSTR, 17,4)        || '-' ||
        SUBSTR(XSTR, 21,4)        || '-' ||
        SUBSTR(XSTR, 24,4)        || '-' ||
        SUBSTR(XSTR, 28,4);
END RANDOM_GUID;

Example of GUID genedrated by the function above:
8EA4-196D-BC48-9793-8AE8-5500-03DC-9D04

回答8:

If you need non-sequential guids you can send the sys_guid() results through a hashing function (see https://stackoverflow.com/a/22534843/1462295 ). The idea is to keep whatever uniqueness is used from the original creation, and get something with more shuffled bits.

For instance:

LOWER(SUBSTR(STANDARD_HASH(SYS_GUID(), 'SHA1'), 0, 32))

Example showing default sequential guid vs sending it through a hash:

SELECT LOWER(SYS_GUID()) AS OGUID FROM DUAL
UNION ALL
SELECT LOWER(SYS_GUID()) AS OGUID FROM DUAL
UNION ALL
SELECT LOWER(SYS_GUID()) AS OGUID FROM DUAL
UNION ALL
SELECT LOWER(SYS_GUID()) AS OGUID FROM DUAL
UNION ALL
SELECT LOWER(SUBSTR(STANDARD_HASH(SYS_GUID(), 'SHA1'), 0, 32)) AS OGUID FROM DUAL
UNION ALL
SELECT LOWER(SUBSTR(STANDARD_HASH(SYS_GUID(), 'SHA1'), 0, 32)) AS OGUID FROM DUAL
UNION ALL
SELECT LOWER(SUBSTR(STANDARD_HASH(SYS_GUID(), 'SHA1'), 0, 32)) AS OGUID FROM DUAL
UNION ALL
SELECT LOWER(SUBSTR(STANDARD_HASH(SYS_GUID(), 'SHA1'), 0, 32)) AS OGUID FROM DUAL

output

80c32a4fbe405707e0531e18980a1bbb
80c32a4fbe415707e0531e18980a1bbb
80c32a4fbe425707e0531e18980a1bbb
80c32a4fbe435707e0531e18980a1bbb
c0f2ff2d3ef7b422c302bd87a4588490
d1886a8f3b4c547c28b0805d70b384f3
a0c565f3008622dde3148cfce9353ba7
1c375f3311faab15dc6a7503ce08182c

来源：https://stackoverflow.com/questions/3037462/how-to-generate-a-guid-in-oracle

标签

Oracle

guid