Question

I’ve the following procedure which says can't reopen table why it is giving this error.Here is the query:

DECLARE rangee INT;
DECLARE uid BIGINT;

SET @rangee = plimitRange * 10; 
SET @uid    = puserid;

DROP TEMPORARY TABLE IF EXISTS Rangee;
CREATE TEMPORARY TABLE Rangee(max BIGINT,min BIGINT);

PREPARE STMT FROM
'INSERT INTO Rangee
select max(postid),MIN(postid) from
(
select wall.postid from wall,posts where  
wall.postid = posts.postid and posts.userid=?
order by wall.postid desc LIMIT 10 OFFSET ?
)m;
';

 EXECUTE STMT USING @uid,@rangee;
 DEALLOCATE PREPARE STMT;


 select comments.comment,comments.postid,user.name,comments.userid 
 from user,posts,comments where 
 posts.postID = comments.postid and 
 comments.postid<=(select max from Rangee) and 
 comments.postid>=(select min from Rangee) and posts.userid = puserid and 
 user.userid=comments.userid order by comments.postid desc;

Here I am inserting values min and max id's in a temporary table from another table so that I can then use those values to retrieve my data in the final query.But in the final query where I am specifying the range i.e the line containing (select max from Rangee) and (select min from Rangee) is giving this error.How can I solve it.The values of min and max are returning fine.

Answer 1

<UPDATE>

Then forget about the whole procedure, do it in one query:

select comments.comment,comments.postid,user.name,comments.userid 
 from 
 user
 INNER JOIN comments ON user.userid=comments.userid
 INNER JOIN posts ON posts.postID = comments.postid
 WHERE 
 comments.postid <=  
 (select MAX(postid) from
    (
    select wall.postid from wall,posts where  
    wall.postid = posts.postid and posts.userid=?
    order by wall.postid desc LIMIT 10 OFFSET ?
    )sq1
 )

 and 
 comments.postid >= 
 (select MIN(postid) from
    (
    select wall.postid from wall,posts where  
    wall.postid = posts.postid and posts.userid=?
    order by wall.postid desc LIMIT 10 OFFSET ?
    )sq2
 ) 
 and 
 posts.userid = puserid 
 order by comments.postid desc;

That’s it.

</UPDATE>

old answer…

DECLARE rangee INT;
DECLARE uid BIGINT;

SET @rangee = plimitRange * 10; 
SET @uid    = puserid;

PREPARE STMT FROM
'select @max_postid := MAX(postid), @min_postid := MIN(postid) from
(
select wall.postid from wall,posts where  
wall.postid = posts.postid and posts.userid=?
order by wall.postid desc LIMIT 10 OFFSET ?
)m;
';

 EXECUTE STMT USING @uid,@rangee;
 DEALLOCATE PREPARE STMT;


 select comments.comment,comments.postid,user.name,comments.userid 
 from user,posts,comments where 
 posts.postID = comments.postid and 
 comments.postid<=@max_postid and 
 comments.postid>=@min_postid and posts.userid = puserid and 
 user.userid=comments.userid order by comments.postid desc;

You don’t need a temporary table at all. Also it would have been bad to do comments.postid <= (select max from Rangee) since this could potentially return more than one row. You should have at least used comments.postid <= (select MAX(max) from Rangee).

Also read this.