DROP TABLE IF EXISTS t1, t2, t3, t4, t5; CREATE TABLE t1 (c1 varchar(100)) ENGINE=MyISAM; CREATE TABLE t2 (c1 varchar(100)) ENGINE=MyISAM; CREATE TABLE t3 (c1 varchar(100)) ENGINE=InnoDB; INSERT INTO t1 VALUES ('Ann'), ('Alice'); INSERT INTO t2 VALUES ('Bob'), ('Brian'); INSERT INTO t3 VALUES ('Chris'), ('Charlie'); CREATE TABLE t4 (c1 varchar(100)) ENGINE=MRG_MYISAM UNION=(t1,t2) INSERT_METHOD=LAST; CREATE TABLE t5 (c1 varchar(100)) ENGINE=MRG_MYISAM UNION=(t1,t3) INSERT_METHOD=LAST; SELECT * FROM t5; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist SELECT * FROM t4; c1 Ann Alice Bob Brian ALTER TABLE t2 ENGINE=InnoDB; SELECT * FROM t4; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist DELETE FROM t2 LIMIT 1; SELECT * FROM t4; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist INSERT INTO t4 VALUES ('Beware'); ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist SELECT * FROM t4; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist SELECT * FROM t2; c1 Brian SELECT * FROM t1; c1 Ann Alice DROP TABLE t1, t2, t3, t4, t5; create table t1 (c1 varchar(100)); create table t2 (c1 varchar(100)); create view t3 as select * from t1; insert into t1 values ('ann'), ('alice'); insert into t2 values ('bob'), ('brian'); create temporary table t4 (c1 varchar(100)) engine=MERGE union=(t2, t1); create temporary table t5 (c1 varchar(100)) engine=MERGE union=(t3, t1); select * from t5; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist lock tables t1 read, t2 read, t3 read, t4 read; select * from t5; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist select * from t4; c1 bob brian ann alice unlock tables; drop table t2; create view t2 as select * from t1; select * from t4; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist lock tables t1 read, t2 read, t3 read; select * from t4; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist select * from t4; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist select * from t4; ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist unlock tables; drop view t2, t3; drop table t1;