Call API on Postman receive a relation error?

i have a problem that when i call api to test my routes in order to insert a record into the database. I checked on postman but it return an error and i do not know how to hadndle this error. My issues demonstrate below:

Router: Method POST

localhost:8080/api/users

Then i try to add records on post man with JSON as below:

{
    "username":"An",
    "password":"123",
    "full_name":"An Nguyễn",
    "email":"an@gmail.com",
    "role_id":"1",
    "is_active":"1",
    "created_date":"09/23/2022",
    "created_by":"An_1",
    "updated_date":"09/24/2022",
    "updated_by":"An_2"
}

Finally, i got this error, how to fix this and if there is any missing please let me know:

{
    "message": "relation \"users\" does not exist"
}