DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a <INT_COLUMN> DEFAULT '0') ENGINE=<STORAGE_ENGINE> <CUSTOM_TABLE_OPTIONS>;
SHOW COLUMNS IN t1;
Field	Type	Null	Key	Default	Extra
a	int(11)	#		0	
INSERT INTO t1 (a) VALUES (1);
SELECT a FROM t1;
a
1
ALTER TABLE t1 ADD COLUMN b <CHAR_COLUMN> DEFAULT '';
SHOW COLUMNS IN t1;
Field	Type	Null	Key	Default	Extra
a	int(11)	#		0	
b	char(8)	#			
INSERT INTO t1 (b) VALUES ('a');
SELECT a,b FROM t1;
a	b
0	a
1	
DROP TABLE t1;