drop table if exists t1,t2,t3,t4,T1; create table T1 (id int primary key, Word varchar(40) not null, Index(Word)); create table t4 (id int primary key, Word varchar(40) not null); INSERT INTO T1 VALUES (1, 'a'), (2, 'b'), (3, 'c'); INSERT INTO T4 VALUES(1,'match'); SELECT * FROM t1; id Word 1 a 2 b 3 c SELECT T1.id from T1 LIMIT 1; id 1 SELECT T2.id from t1 as T2 LIMIT 1; id 1 SELECT * from t1 left join t4 on (test.t1.id= TEST.t4.id) where TEST.t1.id >= test.t4.id; id Word id Word 1 a 1 match SELECT T2.id from t1 as t2 LIMIT 1; Unknown table 'T2' in field list RENAME TABLE T1 TO T2; ALTER TABLE T2 ADD new_col int not null; ALTER TABLE T2 RENAME T3; show tables like 't_'; Tables_in_test (t_) t3 t4 drop table t3,t4; create table t1 (a int); select count(*) from T1; count(*) 0 select count(*) from t1; count(*) 0 select count(T1.a) from t1; Unknown table 'T1' in field list select count(bags.a) from t1 as Bags; Unknown table 'bags' in field list drop table t1;