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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 partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL system NULL NULL NULL NULL 1 100.00 NULL
Warnings:
Warning 1681 'EXTENDED' is deprecated and will be removed in a future release.
Note 1003 /* select#1 */ 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 partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 NULL system NULL NULL NULL NULL 1 100.00 NULL
Warnings:
Note 1003 /* select#1 */ select '' AS `str`,'' AS `strnull`,'0' AS `intg`,'0' AS `rel` from dual where ('' <> default(''))
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;