General error: 1 OCIStmtExecute: ORA-00001: unique constraint (HR.SYS_C004023) violated ?

Question

Hi, I can identify the error message that its due to unique value constraint, my table is 'branches',and where did SYS_C004023 come. I have checked the branches table and there is no value duplication. What could be the issue.

Answer 1

where did SYS_C004023 come

This is a system-generated constraint name, which Oracle creates when a constraint is created without being explicitly named e.g.

create table mytable (col1 integer primary key);

The primary key constraint on mytable will be system-generated since I didn't explicitly name it like this:

create table mytable (col1 integer constraint mytable_pk primary key);

You can find out what table this constraint is on like this:

select table_name
from all_constraints
where owner = 'HR'
and constraint_name = 'SYS_C004023';

And you can find out which columns it makes unique like this:

select column_name
from all_cons_columns
where owner = 'HR'
and constraint_name = 'SYS_C004023';

there is no value duplication

No, there won't be, thanks to the constraint. What there has been is a failed attempt to insert or update a row so that the uniqueness constraint is violatedd.