How to modify sequence in oracle

Method: 1. Use the "ALTER SEQUENCE sequence name" statement to modify the sequence name; 2. Use "Increment By" to modify the sequence initial value. The syntax is "ALTER SEQUENCE SEQ_TEST INCREMENT BY value".

The operating environment of this tutorial: Windows 10 system, Oracle 11g version, Dell G3 computer.

How oracle modifies the sequence

Oracle Create sequence: create sequence xxxx

Note: The sequence in Oracle is not the same as the auto-increment in MySQL , continuous, but jumpy and discontinuous. If you want to make it continuous, you must specify the relevant attributes and values.

1 create sequence student_id

2 minvalue 1 --Minimum value

3 nomaxvalue --Do not set the maximum value (determined by the machine), or based on the value range of the table field Set maxvalue

4 maxvalue 999 -- Maximum value

5 start with 1 --Start counting from 1, the value is variable

6 increment by 1 --Increment each time 1. Variable value

7 nocycle --Always accumulate, no cycle; cycle: after reaching the maximum value, it will accumulate from the beginning

8 nocache; --Do not build a buffer. If you create a cache, the system will automatically read the cache value seq, which will speed up the running speed; if you use the cache in a single machine, or the oracle is dead, the seq value read next time will be incoherent, so it is not recommended to use the cache.

2. Oracle modify sequence: alter sequence xxxx

1 alter sequence student_id -- the sequence name can also be changed

2 minvalue 1

3 maxvalue 99999

4 start with 1

5 increment by 1

6 cycle -- after reaching 99999, start from scratch

7 nocache ;

3. Modify the initial value through Increment By.

For example: If the sequence name is SEQ_TEST, the initial value is 13, and now you want to set the initial value to 1013, the Increment By value is: 1000(1013-13)

1) Execution: ALTER SEQUENCE SEQ_TEST INCREMENT BY 1000;

2) Execution: SELECT SEQ_TEST.NEXTVAL FROM DUAL;

3) Execution: ALTER SEQUENCE SEQ_TEST INCREMENT BY 1;

Recommended Tutorial: "Oracle Video Tutorial"

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