Saturday, December 13, 2008

Create sequence oracle

Creating sequence in oracle is a very easy task.
Sequences help more at instants like generating new id for a record that has been inserted into oracle table through triggers.

create sequence [sequence_name] start with [sequence start from] increment by [increment by] [caching]
Nocache clause is used while creating sequence to generate sequences in an order
Example :-
create sequence seq_test start with 1 increment by 1 nocache

Once sequence is created , value can be retrieved using sequence name as
syntax :- select [sequence name].nextval from dual
Example :- select seq_test.nextval from dual.

next_val increments the current value of the sequence and returns the updated value.

Simmillalry to get current value of the sequence we should use currval.
Example :-
select seq_test.currval from dual

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