MariaDB 10.5

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select version();


version()


10.5.13-MariaDB


create table t (i int default '111',
nm char(20) NOT NULL DEFAULT SUBSTRING_INDEX(current_user(),'@',1),
hst char(20) NOT NULL DEFAULT SUBSTRING_INDEX(current_user(),'@',-1));
show create table t;


Table
Create Table


t
CREATE TABLE `t` (
  `i` int(11) DEFAULT 111,
  `nm` char(20) NOT NULL DEFAULT substring_index(current_user(),'@',1),
  `hst` char(20) NOT NULL DEFAULT substring_index(current_user(),'@',-1)
) ENGINE=InnoDB DEFAULT CHARSET=latin1


insert into t (i) values(1),(2),(3);
insert into t (i,nm,hst) values(1,'Iam','192.168.1.1');
select * from t;


i
nm
hst


1
u_441103756
localhost

2
u_441103756
localhost

3
u_441103756
localhost

1
Iam
192.168.1.1

i	nm	hst
1	u_441103756	localhost
2	u_441103756	localhost
3	u_441103756	localhost
1	Iam	192.168.1.1