在Oracle中似乎没有AUTO_INCREMENT的概念,直到并且包括版本11g。
如何在Oracle 11g中创建一个行为像自动递增的列?
在Oracle中似乎没有AUTO_INCREMENT的概念,直到并且包括版本11g。
如何在Oracle 11g中创建一个行为像自动递增的列?
当前回答
create trigger t1_trigger
before insert on AUDITLOGS
for each row
begin
select t1_seq.nextval into :new.id from dual;
end;
我只需要改变表名(AUDITLOGS)与你的表名和新的。使用new.column_name标识
其他回答
FUNCTION GETUNIQUEID_2 RETURN VARCHAR2
AS
v_curr_id NUMBER;
v_inc NUMBER;
v_next_val NUMBER;
pragma autonomous_transaction;
begin
CREATE SEQUENCE sequnce
START WITH YYMMDD0000000001
INCREMENT BY 1
NOCACHE
select sequence.nextval into v_curr_id from dual;
if(substr(v_curr_id,0,6)= to_char(sysdate,'yymmdd')) then
v_next_val := to_number(to_char(SYSDATE+1, 'yymmdd') || '0000000000');
v_inc := v_next_val - v_curr_id;
execute immediate ' alter sequence sequence increment by ' || v_inc ;
select sequence.nextval into v_curr_id from dual;
execute immediate ' alter sequence sequence increment by 1';
else
dbms_output.put_line('exception : file not found');
end if;
RETURN 'ID'||v_curr_id;
END;
SYS_GUID返回一个GUID——一个全局唯一的ID。SYS_GUID是RAW(16)。它不会生成递增的数值。
如果你想要创建一个递增的数字键,你需要创建一个序列。
CREATE SEQUENCE name_of_sequence
START WITH 1
INCREMENT BY 1
CACHE 100;
然后,您可以在INSERT语句中使用该序列
INSERT INTO name_of_table( primary_key_column, <<other columns>> )
VALUES( name_of_sequence.nextval, <<other values>> );
或者您可以定义一个触发器,该触发器使用序列自动填充主键值
CREATE OR REPLACE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
SELECT name_of_sequence.nextval
INTO :new.primary_key_column
FROM dual;
END;
如果您使用的是Oracle 11.1或更高版本,可以稍微简化触发器
CREATE OR REPLACE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
:new.primary_key_column := name_of_sequence.nextval;
END;
如果您真的想使用SYS_GUID
CREATE TABLE table_name (
primary_key_column raw(16) default sys_guid() primary key,
<<other columns>>
)
查询如何在oracle中创建自动增量。在下面的查询中,每当插入新行时,列值将自动递增
CREATE TABLE table1(
id RAW(16) NOT NULL ENABLE,
incrmnt NUMBER(10,0) GENERATED ALWAYS AS IDENTITY
MINVALUE 1 MAXVALUE 999999999999999999999999999 INCREMENT BY 1 START WITH 1 NOORDER NOCYCLE NOT NULL ENABLE,
CONSTRAINT PK_table1 PRIMARY KEY (id) ENABLE);
在Oracle 11g中没有“auto_increment”或“identity”列这样的东西。然而,你可以很容易地用一个序列和一个触发器来建模:
表定义:
CREATE TABLE departments (
ID NUMBER(10) NOT NULL,
DESCRIPTION VARCHAR2(50) NOT NULL);
ALTER TABLE departments ADD (
CONSTRAINT dept_pk PRIMARY KEY (ID));
CREATE SEQUENCE dept_seq START WITH 1;
触发器定义:
CREATE OR REPLACE TRIGGER dept_bir
BEFORE INSERT ON departments
FOR EACH ROW
BEGIN
SELECT dept_seq.NEXTVAL
INTO :new.id
FROM dual;
END;
/
更新:
IDENTITY列现在可以在Oracle 12c上使用:
create table t1 (
c1 NUMBER GENERATED by default on null as IDENTITY,
c2 VARCHAR2(10)
);
或者指定起始值和增量值,同时防止任何插入标识列(GENERATED ALWAYS)(同样,仅适用于Oracle 12c+)
create table t1 (
c1 NUMBER GENERATED ALWAYS as IDENTITY(START with 1 INCREMENT by 1),
c2 VARCHAR2(10)
);
另外,Oracle 12也允许使用一个序列作为默认值:
CREATE SEQUENCE dept_seq START WITH 1;
CREATE TABLE departments (
ID NUMBER(10) DEFAULT dept_seq.nextval NOT NULL,
DESCRIPTION VARCHAR2(50) NOT NULL);
ALTER TABLE departments ADD (
CONSTRAINT dept_pk PRIMARY KEY (ID));
这是我如何在一个现有的表和列(名为id)上做到这一点:
UPDATE table SET id=ROWNUM;
DECLARE
maxval NUMBER;
BEGIN
SELECT MAX(id) INTO maxval FROM table;
EXECUTE IMMEDIATE 'DROP SEQUENCE table_seq';
EXECUTE IMMEDIATE 'CREATE SEQUENCE table_seq START WITH '|| TO_CHAR(TO_NUMBER(maxval)+1) ||' INCREMENT BY 1 NOMAXVALUE';
END;
CREATE TRIGGER table_trigger
BEFORE INSERT ON table
FOR EACH ROW
BEGIN
:new.id := table_seq.NEXTVAL;
END;