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nextval

1. NEXTVAL Function​

The NEXTVAL function in H2 database is used to retrieve the next value from a sequence.

2. Syntax​

The syntax for the NEXTVAL function in H2 database is as follows:

NEXTVAL(sequence_name)

Arguments​

  • sequence_name: The name of the sequence from which the next value needs to be retrieved. It should be a valid sequence name.

Return​

  • The NEXTVAL function returns the next value from the specified sequence.

3. Notes​

  • The NEXTVAL function in H2 database is typically used in conjunction with sequences to generate unique identifiers or primary keys for tables.
  • If the specified sequence does not exist, an error will be thrown.
  • The NEXTVAL function automatically increments the sequence value by 1.
  • The returned value is of the same datatype as the sequence.

4. Examples​

Here are a few examples demonstrating the usage of the NEXTVAL function in H2 database:

Example 1 - Retrieving the next value from a sequence:​

CREATE SEQUENCE seq START WITH 1;

SELECT NEXTVAL('seq') AS next_value;

Output:

next_value
----------
1

Example 2 - Using NEXTVAL to generate primary keys:​

CREATE TABLE employees (
  id INT PRIMARY KEY DEFAULT NEXTVAL('seq'),
  name VARCHAR(50),
  age INT
);

INSERT INTO employees (name, age) VALUES ('John Doe', 30), ('Jane Smith', 25);

SELECT * FROM employees;

Output:

id |    name    | age
---+------------+-----
1  | John Doe   | 30
2  | Jane Smith | 25
  • currval - Retrieve the current value from a sequence
  • SETVAL - Set the value of a sequence