Getting around MySQL "Can't reopen table" error

A simple solution is to duplicate the temporary table. Works well if the table is relatively small, which is often the case with temporary tables.

Right, the MySQL docs say: "You cannot refer to a TEMPORARY table more than once in the same query."

Here's an alternative query that should find the same rows, although all the conditions of matching rows won't be in separate columns, they'll be in a comma-separated list.

SELECT f1.baseID, GROUP_CONCAT(f1.condition)
FROM search f1
WHERE f1.condition IN (<condition1>, <condition2>, ... <conditionN>)
GROUP BY f1.baseID
HAVING COUNT(*) = <N>;

I got around this by creating a permanent "temporary" table and suffixing the SPID (sorry, i'm from SQL Server land) to the table name, to make a unique table name. Then creating dynamic SQL statements to create the queries. If anything bad happens, the table will be dropped and recreated.

I'm hoping for a better option. C'mon, MySQL Devs. The 'bug'/'feature request' has been open since 2008! Seems like all the 'bugs' 've encountered are in the same boat.

select concat('ReviewLatency', CONNECTION_ID()) into @tablename;

#Drop "temporary" table if it exists
set @dsql=concat('drop table if exists ', @tablename, ';');
PREPARE QUERY1 FROM @dsql;
EXECUTE QUERY1;
DEALLOCATE PREPARE QUERY1;

#Due to MySQL bug not allowing multiple queries in DSQL, we have to break it up...
#Also due to MySQL bug, you cannot join a temporary table to itself,
#so we create a real table, but append the SPID to it for uniqueness.
set @dsql=concat('
create table ', @tablename, ' (
    `EventUID` int(11) not null,
    `EventTimestamp` datetime not null,
    `HasAudit` bit not null,
    `GroupName` varchar(255) not null,
    `UserID` int(11) not null,
    `EventAuditUID` int(11) null,
    `ReviewerName` varchar(255) null,
    index `tmp_', @tablename, '_EventUID` (`EventUID` asc),
    index `tmp_', @tablename, '_EventAuditUID` (`EventAuditUID` asc),
    index `tmp_', @tablename, '_EventUID_EventTimestamp` (`EventUID`, `EventTimestamp`)
) ENGINE=MEMORY;');
PREPARE QUERY2 FROM @dsql;
EXECUTE QUERY2;
DEALLOCATE PREPARE QUERY2;

#Insert into the "temporary" table
set @dsql=concat('
insert into ', @tablename, ' 
select e.EventUID, e.EventTimestamp, e.HasAudit, gn.GroupName, epi.UserID, eai.EventUID as `EventAuditUID`
    , concat(concat(concat(max(concat('' '', ui.UserPropertyValue)), '' (''), ut.UserName), '')'') as `ReviewerName`
from EventCore e
    inner join EventParticipantInformation epi on e.EventUID = epi.EventUID and epi.TypeClass=''FROM''
    inner join UserGroupRelation ugr on epi.UserID = ugr.UserID and e.EventTimestamp between ugr.EffectiveStartDate and ugr.EffectiveEndDate 
    inner join GroupNames gn on ugr.GroupID = gn.GroupID
    left outer join EventAuditInformation eai on e.EventUID = eai.EventUID
    left outer join UserTable ut on eai.UserID = ut.UserID
    left outer join UserInformation ui on eai.UserID = ui.UserID and ui.UserProperty=-10
    where e.EventTimestamp between @StartDate and @EndDate
        and e.SenderSID = @FirmID
    group by e.EventUID;');
PREPARE QUERY3 FROM @dsql;
EXECUTE QUERY3;
DEALLOCATE PREPARE QUERY3;

#Generate the actual query to return results. 
set @dsql=concat('
select rl1.GroupName as `Group`, coalesce(max(rl1.ReviewerName), '''') as `Reviewer(s)`, count(distinct rl1.EventUID) as `Total Events`
    , (count(distinct rl1.EventUID) - count(distinct rl1.EventAuditUID)) as `Unreviewed Events`
    , round(((count(distinct rl1.EventUID) - count(distinct rl1.EventAuditUID)) / count(distinct rl1.EventUID)) * 100, 1) as `% Unreviewed`
    , date_format(min(rl2.EventTimestamp), ''%W, %b %c %Y %r'') as `Oldest Unreviewed`
    , count(distinct rl3.EventUID) as `<=7 Days Unreviewed`
    , count(distinct rl4.EventUID) as `8-14 Days Unreviewed`
    , count(distinct rl5.EventUID) as `>14 Days Unreviewed`
from ', @tablename, ' rl1
left outer join ', @tablename, ' rl2 on rl1.EventUID = rl2.EventUID and rl2.EventAuditUID is null
left outer join ', @tablename, ' rl3 on rl1.EventUID = rl3.EventUID and rl3.EventAuditUID is null and rl1.EventTimestamp > DATE_SUB(NOW(), INTERVAL 7 DAY) 
left outer join ', @tablename, ' rl4 on rl1.EventUID = rl4.EventUID and rl4.EventAuditUID is null and rl1.EventTimestamp between DATE_SUB(NOW(), INTERVAL 7 DAY) and DATE_SUB(NOW(), INTERVAL 14 DAY)
left outer join ', @tablename, ' rl5 on rl1.EventUID = rl5.EventUID and rl5.EventAuditUID is null and rl1.EventTimestamp < DATE_SUB(NOW(), INTERVAL 14 DAY)
group by rl1.GroupName
order by ((count(distinct rl1.EventUID) - count(distinct rl1.EventAuditUID)) / count(distinct rl1.EventUID)) * 100 desc
;');
PREPARE QUERY4 FROM @dsql;
EXECUTE QUERY4;
DEALLOCATE PREPARE QUERY4;

#Drop "temporary" table
set @dsql = concat('drop table if exists ', @tablename, ';');
PREPARE QUERY5 FROM @dsql;
EXECUTE QUERY5;
DEALLOCATE PREPARE QUERY5;