#1222 - The used SELECT statements have a different number of columns

Question

Why am i getting a #1222 - The used SELECT statements have a different number of columns ? i am trying to load wall posts from this users friends and his self.

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Answer 1

The first statement in the UNION returns four columns:

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

The second one returns six, because the * expands to include all the columns from WALL_POSTS:

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

The UNION and UNION ALL operators require that:

1. The same number of columns exist in all the statements that make up the UNION'd query
2. The data types have to match at each position/column

Use:

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))