title: How to use REGEXP_LIKE Constraint while creating Table
body: <p>Until last night, this worked:</p>
  
  <pre><code>CREATE TABLE UTENTE(
      ID_USER             CHAR(7)         PRIMARY KEY,
      USERNAME            VARCHAR(25)     NOT NULL UNIQUE,
      PASSWORD            VARCHAR(25)     NOT NULL,
      DATA_SIGNUP         DATE            DEFAULT SYSDATE,
      EMAIL               VARCHAR(40)     NOT NULL UNIQUE,
      CONSTRAINT          CK_REG_US       CHECK(REGEXP_LIKE(USERNAME,'^[A-Za-z0-9]$')),
      CONSTRAINT          CK_REG_EM       CHECK(REGEXP_LIKE(EMAIL, '^(\S+)\@(\S+)\.(\S+)$'))
  );
  </code></pre>
  
  <p>Now if I do populate, see this error:</p>
  
  <pre><code>ORA-02290: check constraint (ADMIN.CK_REG_US) violated
  </code></pre>
  
  <p>From yesterday evening to today nothing has changed
  example of insert that violated constraint</p>
  
  <pre><code>INSERT INTO UTENTE (id_user, username, password, data_signup, email) VALUES (SEQ_ID_USER.NEXTVAL, 'npalk0', 'xPtvZl9', '27-APR-2017', 'bbowden0@over-blog.com');
  </code></pre>
  
  <blockquote>
    <p>I solved the problem, $, had to be removed, last night I do not know
    why I put it, thanks to the help</p>
  </blockquote>