n-number of nested inner join - mysql

Question

I have a sql-statement which correctly fetches data from one table. However, I need to fetch in the same way from n number of tables named table_n. All of these tables contain a 3-field primary key of projid, docid and revnr. I need to return n as docType as well, to differentiate the tables. The result will be sorted by projid and/or docid.
I tried sorting all the outputs from the different queries in PHP but it was way too slow (at least a few seconds on a 3MB database). I'm convinced MySQL/MSSQL will do it faster.
This is my current query:
SELECT a.* FROM `table_1` a
INNER JOIN (SELECT docid,
Max(revnr) max_val
FROM `table_1`
WHERE ( projid = something )
GROUP BY docid) b
ON a.docid = b.docid
AND a.revnr = b.max_val ORDER BY docid DESC
My current query gets the rows with highest revnr for each docid and projid.
I'm developing on MySQL but I need it to work on MSSQL as well. A general SQL solution would be great.
Thanks!
EDIT: Table schemas of the tables i currently have:
CREATE TABLE IF NOT EXISTS `table_1` (
`projid` int(11) NOT NULL,
`docid` int(11) NOT NULL,
`revnr` int(11) NOT NULL,
`revname` varchar(64) NOT NULL,
`signedOn` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`sign` int(11) NOT NULL,
`ritningsnr` varchar(128) NOT NULL,
`moment` varchar(256) NOT NULL,
`omrade` varchar(256) NOT NULL,
`start` datetime NOT NULL,
`stop` datetime NOT NULL,
`extTodo` int(11) NOT NULL,
PRIMARY KEY (`projid`,`docid`,`revnr`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COMMENT='egenkontroll';
CREATE TABLE IF NOT EXISTS `table_2` (
`projid` int(11) NOT NULL,
`docid` int(11) NOT NULL,
`revnr` int(11) NOT NULL,
`revname` varchar(64) NOT NULL,
`signedOn` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`sign` int(11) NOT NULL,
`extWater` int(11) NOT NULL,
`extRisk` int(11) NOT NULL,
`extSystem` int(11) NOT NULL,
`extHelp` int(11) NOT NULL,
`extProvtryck` int(11) NOT NULL,
`extDoc` int(11) NOT NULL,
`extEgenkontroll` int(11) NOT NULL COMMENT 'exttabell',
`extOther` int(11) NOT NULL,
`extMontorer` int(11) NOT NULL,
PRIMARY KEY (`projid`,`docid`,`revnr`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COMMENT='arbetsberedning';
CREATE TABLE IF NOT EXISTS `table_3` (
`projid` int(11) NOT NULL,
`docid` int(11) NOT NULL,
`revnr` int(11) NOT NULL,
`revname` varchar(64) NOT NULL,
`adress` varchar(256) NOT NULL,
`pipesMark` tinyint(1) NOT NULL,
`pipesKulvert` tinyint(1) NOT NULL,
`pipesBasement` tinyint(1) NOT NULL,
`pipesVaning` tinyint(1) NOT NULL,
`pipesIngjutna` tinyint(1) NOT NULL,
`ledningTappvatten` tinyint(1) NOT NULL,
`ledningVarmevatten` tinyint(1) NOT NULL,
`ledningHetvatten` tinyint(1) NOT NULL,
`ledningKylaPrim` tinyint(1) NOT NULL,
`ledningKylaSek` tinyint(1) NOT NULL,
`ledningGas` tinyint(1) NOT NULL,
`ledningLuft` tinyint(1) NOT NULL,
`ledningAvlopp` tinyint(1) NOT NULL,
`ledningOther` varchar(512) NOT NULL,
`materialGjutjarn` tinyint(1) NOT NULL,
`materialSteel` tinyint(1) NOT NULL,
`materialKoppar` tinyint(1) NOT NULL,
`materialPlast` tinyint(1) NOT NULL,
`materialRostfritt` tinyint(1) NOT NULL,
`materialOther` varchar(512) NOT NULL,
`omfattningLength` int(11) NOT NULL COMMENT 'meter',
`omfattningDimension` varchar(16) NOT NULL,
`omfattningRitningnr` varchar(128) NOT NULL,
`doneWithPump` tinyint(1) NOT NULL,
`doneWithVattenledning` tinyint(1) NOT NULL,
`doneWithKompressor` tinyint(1) NOT NULL,
`doneWithTathetsprovare` tinyint(1) NOT NULL,
`tryckmedieVatten` tinyint(1) NOT NULL,
`tryckmedieLuft` tinyint(1) NOT NULL,
`tryckmedieOther` varchar(128) NOT NULL,
`manometerDiameter` int(11) NOT NULL COMMENT 'mm',
`manometerGradering` int(11) NOT NULL COMMENT 'kPa',
`manometerReadPressure` int(11) NOT NULL,
`manometerTid` int(11) NOT NULL COMMENT 'sekunder',
`testedOn` datetime NOT NULL,
`testedBy` varchar(128) NOT NULL COMMENT '"id_" + (userid)',
`comments` varchar(1024) NOT NULL,
`commentsBy` varchar(128) NOT NULL COMMENT '"id_" + (userid)',
`signedOn` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`sign` int(11) NOT NULL,
PRIMARY KEY (`projid`,`docid`,`revnr`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
The fields I need are projid, docid, revnr, revname, signedOn, sign and are present in all current and future tables.