于是记录... [user.]sequence_name; 从数据库中删除一序列。 创建一个序列号的语句: CREATESEQUENCEEXAM_NO_SEQ START WITH 1484 MAXVALUE oracle序列概念,如何创建,修改和使用序列? 插入语句中引用,也可以通过查询检查当前值,或使序列增至下一个值。 创建序列createsequenceseq_ten
Use NOCYCLE if you want the sequence to stop generating the next value when it reaches its limit. This is the default. CACHE Specify the number of sequence values that Oracle will preallocate and keep in the memory for faster access. ...
-- Accessing current sequence value without incrementing SELECT EXAMPLE_SEQUENCE.currval FROM dual; 但是,当您需要一个接一个地检索序列中的一个值时,请使用 NEXTVAL: -- Accessing the next sequence value SELECT EXAMPLE_SEQUENCE.nextval FROM dual; 正如您所看到的,每次执行此查询时,Oracle 都会从我们之前...
其中last即为 Sequence 在 Session 中的当前值,即 current_value,cached为 Sequence 在 Session 中的缓存值,即 cached_value,increment记录了步长,有了这三个值即可满足 Sequence 缓存的基本条件。 对于Sequence Session Cache 与页面值之间的关系,如下图所示: 类似于log_cnt,cache_cnt即为用户在定义 Sequence 时,...
`current_value` int(11) NOT NULL, `increment_value` int(11) NOT NULL DEFAULT '1', PRIMARY KEY (`seq_name`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; 二、创建三个函数 1、func_currval:获取当前序列的值并返回 CREATE FUNCTION `func_currval`(seq_name varchar(50)) ...
更多信息,参考Oracle 联机文档: CACHE CACHE(CEIL (MAXVALUE - MINVALUE)) / ABS (INCREMENT) CACHENote: CACHENOCACHE NOCACHECACHENOCACHEORDERto guarantee that sequence numbers are generated in order of request. This clause is useful if you are using the sequence numbers as timestamps. Guaranteeing...
The syntax to create a sequence in Oracle is: CREATE SEQUENCE sequence_name MINVALUE value MAXVALUE value START WITH value INCREMENT BY value CACHE value; sequence_name The name of the sequence that you wish to create. Example Let's look at an example of how to create a sequence in Oracl...
The DROP SEQUENCE statement is also useful in case you want to restart a sequence. For example, if you have a sequence with the current value of 100 and you want to restart the sequence with a value of 50, then you can drop the sequence and re-create it with a START VALUE of 50....
set value = 0; select current_val into value from sequence where seq_name = v_seq_name; return value; end; 4.测试当前值 select currval('seq_test1_num1'); 5.创建下一个值 create function nextval (v_seq_name VARCHAR(50)) returns integer ...
模拟oracle中sequence实现 新建查询 1、创建表tb_sequence,用来存放sequence值: create table tb_sequence(name varchar(50) not null,current_value int not null,_increment int not null default 1, primary key(name)); 1. 2、手动插入数据: insert into tb_sequence values('userid',100,2); ...