drop table if exists t1,t2;
create table t1(str varchar(10) default 'def',strnull varchar(10),intg int default '10',rel double default '3.14');
insert into t1 values ('','',0,0.0);
select default(str), default(strnull), default(intg), default(rel) from t1;
default(str)	default(strnull)	default(intg)	default(rel)
def	NULL	10	3.14
explain extended select default(str), default(strnull), default(intg), default(rel) from t1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
Warnings:
Note	1003	select default('') AS `default(str)`,default('') AS `default(strnull)`,default(0) AS `default(intg)`,default(0) AS `default(rel)` from dual
select * from t1 where str <> default(str);
str	strnull	intg	rel
		0	0
explain select * from t1 where str <> default(str);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	
drop table t1;
CREATE TABLE t1 (id int(11), s varchar(20));
INSERT INTO t1 VALUES (1, 'one'), (2, 'two'), (3, 'three');
SELECT s, 32 AS mi FROM t1 GROUP BY s HAVING DEFAULT(mi) IS NULL;
ERROR HY000: Field 'mi' doesn't have a default value
DROP TABLE t1;
set timestamp=unix_timestamp('2001-01-01 10:20:30.123456');
create table t1 (a int default 1, b int default (a+1),
c varchar(100) default 'foo', d text default 'bar',
e timestamp default now(), f timestamp(6) default now(2));
insert t1 () values ();
insert t1 (a) values (10);
select default(a),default(b),default(c),default(d),default(e),default(f) from t1;
default(a)	default(b)	default(c)	default(d)	default(e)	default(f)
1	2	foo	bar	2001-01-01 10:20:30	2001-01-01 10:20:30.120000
1	11	foo	bar	2001-01-01 10:20:30	2001-01-01 10:20:30.120000
drop table t1;