#1222 - De brugte SELECT-sætninger har et andet antal kolonner

Den første sætning i UNION returnerer fire kolonner:

SELECT b.id AS id, 
       b.pid AS pid, 
       b.message AS message, 
       b.date AS date 
  FROM wall_posts AS b 

Den anden returnerer seks , fordi * udvides til at inkludere alle kolonnerne fra WALL_POSTS :

SELECT b.id, 
       b.date, 
       b.privacy,
       b.pid. 
       b.uid message
  FROM wall_posts AS b 

UNION og UNION ALL operatører kræver, at:

1. Det samme antal kolonner findes i alle de udsagn, der udgør UNION-forespørgslen
2. Datatyperne skal matche ved hver position/kolonne

Brug:

FROM ((SELECT b.id AS id, 
             b.pid AS pid, 
             b.message AS message, 
             b.date AS date 
        FROM wall_posts AS b 
        JOIN Friends AS f ON f.id = b.pid 
       WHERE f.buddy_id = '1' AND f.status = 'b'
    ORDER BY date DESC
       LIMIT 0, 10)
      UNION
      (SELECT id,
              pid,
              message,
              date
         FROM wall_posts
        WHERE pid = '1'
     ORDER BY date DESC
        LIMIT 0, 10))