I like the beginning, only t1, t2 two table
The CREATE TABLE t1 (a INT the NOT NULL AUTO_INCREMENT PRIMARY KEY, the message CHAR (20)) engine=myisam;

The CREATE TABLE t2 (a INT the NOT NULL AUTO_INCREMENT PRIMARY KEY, the message CHAR (20)) engine=myisam;

The CREATE TABLE total (a INT the NOT NULL AUTO_INCREMENT PRIMARY KEY, the message CHAR (20)) ENGINE=MERGE UNION=(t1, t2) INSERT_METHOD=LAST;

Data behind the t2 data of more than 1 million, I need to create winter t3 table appended to the total total table
ALTERTABLE total ENGINE=MERGE UNION=(t3) INSERT_METHOD=LAST;
Such written above is wrong, I want to know can be supplemented by t3 table, behind if you don't have one thousand tables, ten thousand tables will be very trouble

This is just a hypothesis, just want to know whether can be supplemented by t3 into total table