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(`test`.`t1`.`str`) AS `default(str)`,default(`test`.`t1`.`strnull`) AS `default(strnull)`,default(`test`.`t1`.`intg`) AS `default(intg)`,default(`test`.`t1`.`rel`) 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 create view v1 as select default(str), default(strnull), default(intg), default(rel) from t1; select * from v1; default(str) default(strnull) default(intg) default(rel) def NULL 10 3.14 show create view v1; View Create View character_set_client collation_connection v1 CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select default(`t1`.`str`) AS `default(str)`,default(`t1`.`strnull`) AS `default(strnull)`,default(`t1`.`intg`) AS `default(intg)`,default(`t1`.`rel`) AS `default(rel)` from `t1` latin1 latin1_swedish_ci drop view v1; 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;