title: Conversion failed when converting the varchar value '' to data type Bit
body: <p>I am testing my insert statement:</p>
  
  <pre><code>insert into Gebruiker
  values ('Sonja123', 'Sonja', 'Van der Vliet', 'kastanjelaan 45',NULL, '3771jx', 'Heteren', 'Nederland', '1980-04-01','Pdel42@hotmail.com', 'WEBM1MAMV', 1, 'Poekie', 'wel')
  </code></pre>
  
  <p>But every time I try to test it, I get the error:</p>
  
  <blockquote>
    <p>Conversion failed when converting the varchar value 'wel' to data type Bit. </p>
  </blockquote>
  
  <p>My trigger is: </p>
  
  <pre><code>CREATE TRIGGER TR_CHECKVERKOPER
     ON  Gebruiker
     FOR INSERT
  AS 
  BEGIN
      DECLARE @USER_NAME VARCHAR(70)
      SET @USER_NAME = (SELECT gebruikersnaam FROM INSERTED)
  
      IF (SELECT Verkoper FROM Gebruiker WHERE gebruikersnaam = @USER_NAME) = 'wel'
      BEGIN
          IF (SELECT COUNT(*) FROM Verkoper WHERE Gebruiker = @USER_NAME) = 0
          BEGIN
              UPDATE Gebruiker SET Verkoper = 'niet' WHERE gebruikersnaam = @USER_NAME    
          END
      END
  END
  GO
  </code></pre>
  
  <p>How can I fix it?</p>