当所有3个表都具有相同的列MYSQL时使用JOIN

Question

I have 3 tables they are...

• posts_deletedPosts
• posts_archivedPosts
• posts_newPosts

I am writing a function which allows users to see all of their posts and so I want to do a join query to pull all the data from these three tables back in one query.

All three tables has the exact same columns I want to get back, and they are...

• title
• category
• dateCreated
• alias

The query i've written so far I think should work, but when I go to use bind param I get this error.

Warning: mysqli_stmt::bind_result() [mysqli-stmt.bind-result]: Number of bind variables doesn't match number of fields in prepared statement

My query looks like as follows...

  $stmt = $this->conx->prepare("SELECT 
    dp.title, dp.category, dp.dateCreated, dp.alias, 
    ap.title, ap.category, ap.dateCreated, ap.alias, 
    np.title, np.category, np.dateCreated, np.alias 
    FROM posts_deletedPosts AS dp 
        INNER JOIN posts_archivedPosts AS ap 
            ON dp.author = ap.author 
        INNER JOIN posts_newPosts AS np 
            ON dp.author = np.author 
    WHERE dp.author = ? 
    LIMIT 5");

I'm pretty new to web dev but I thought it would be possible to carry out a join like this and return one large dataset. I did use 3 select queries before but I want to build some pagination using AJAX and so I need this data in one complete set preferably.

This is how i bind the parameter

$stmt->bind_param("i",$uid);

Answer 1

You don't need JOIN s, you need UNION s:

SELECT title FROM posts_deletedPosts WHERE author=...
UNION
SELECT title FROM posts_archivedPosts WHERE author=...
UNION
SELECT title FROM posts_newPosts WHERE author=...