Postgresql: Violates check constraint. Failing row contains

Question

I tried to insert some data in a database with postgresql but still showing the same message:

ERROR: new row for relation "empleados" violates check constraint "ck_empleados_documento" DETAIL: Failing row contains (13, 22222222, f, Lopez, Ana, Colon 123, 1, 2, casado , 1990-10-10).

I do not know where or what the error is nor did I find anything that solved this. This is what i try to insert:

insert into empleados (documento, sexo, apellido, nombre, domicilio, idSecc, cantidadhijos, estadocivil, fechaingreso) values('22222222','f','Lopez','Ana','Colon 123',1,2,'casado','1990-10-10');

and this is the structure of the table:

CREATE TABLE public.empleados
(
  idempleado integer NOT NULL DEFAULT nextval('empleados_idempleado_seq'::regclass),
  documento character(8),
  sexo character(1),
  apellido character varying(20),
  nombre character varying(20),
  domicilio character varying(30),
  idsecc smallint NOT NULL,
  cantidadhijos smallint,
  estadocivil character(10),
  fechaingreso date,
  CONSTRAINT pk_empleados PRIMARY KEY (idempleado),
  CONSTRAINT fk_empleados_idsecc FOREIGN KEY (idsecc)
      REFERENCES public.puestos (idpuesto) MATCH SIMPLE
      ON UPDATE CASCADE ON DELETE NO ACTION,
  CONSTRAINT uq_empleados_documento UNIQUE (documento),
  CONSTRAINT ck_empleados_documento CHECK (documento ~~ '[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'::text),
  CONSTRAINT ck_empleados_estadocivil CHECK (estadocivil = ANY (ARRAY['casado'::bpchar, 'divorciado'::bpchar, 'soltero'::bpchar, 'viudo'::bpchar])),
  CONSTRAINT ck_empleados_hijos CHECK (cantidadhijos >= 0),
  CONSTRAINT ck_empleados_sexo CHECK (sexo = ANY (ARRAY['f'::bpchar, 'm'::bpchar]))
)

Answer 1

The error message says your row violates check constraint "ck_empleados_documento".

ck_empleados_documento is defined as

CONSTRAINT ck_empleados_documento CHECK (documento ~~ '[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'::text)

According to https://www.postgresql.org/docs/current/static/functions-matching.html#FUNCTIONS-LIKE:

The operator ~~ is equivalent to LIKE

So your constraint really means

documento LIKE '[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'::text

From the same page:

stringLIKEpattern

If pattern does not contain percent signs or underscores, then the pattern only represents the string itself

Your pattern doesn't contain % or _, so it is equivalent to

documento = '[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'

This can never be true because documento is only 8 characters long.

---

You probably want to do this instead:

documento SIMILAR TO '[0-9]{8}'

SIMILAR TO uses SQL regexes and understands character classes such as [0-9].

Answer 2

I think your ck_empleados_documento should be written like this:

CONSTRAINT ck_empleados_documento CHECK (documento ~ '[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'::text),

Explanation: According to the Postgres Documentation:

The operator ~~ is equivalent to LIKE

If you want pattern matching you need to use Operators:

~       Matches regular expression, case sensitive
~*  Matches regular expression, case insensitive
!~  Does not match regular expression, case sensitive
!~*     Does not match regular expression, case insensitive