select database();
database()
test
select charset(database());
charset(database())
utf8
select database() = "test";
database() = "test"
1
select database() = _utf8"test";
database() = _utf8"test"
1
select database() = _latin1"test";
database() = _latin1"test"
1
select user() like "%@%";
user() like "%@%"
1
select user() like _utf8"%@%";
user() like _utf8"%@%"
1
select user() like _latin1"%@%";
user() like _latin1"%@%"
1
select charset(user());
charset(user())
utf8
select version()>="3.23.29";
version()>="3.23.29"
1
select version()>=_utf8"3.23.29";
version()>=_utf8"3.23.29"
1
select version()>=_latin1"3.23.29";
version()>=_latin1"3.23.29"
1
select charset(version());
charset(version())
utf8
explain extended select database(), user();
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
Warnings:
Note	1003	select database() AS `database()`,user() AS `user()`
create table t1 (version char(60)) select database(), user(), version() as 'version';
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `database()` varchar(34) CHARACTER SET utf8 DEFAULT NULL,
  `user()` varchar(77) CHARACTER SET utf8 NOT NULL DEFAULT '',
  `version` char(60) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
select charset(charset(_utf8'a')), charset(collation(_utf8'a'));
charset(charset(_utf8'a'))	charset(collation(_utf8'a'))
utf8	utf8
select collation(charset(_utf8'a')), collation(collation(_utf8'a'));
collation(charset(_utf8'a'))	collation(collation(_utf8'a'))
utf8_general_ci	utf8_general_ci
create table t1 select charset(_utf8'a'), collation(_utf8'a');
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `charset(_utf8'a')` varchar(64) CHARACTER SET utf8 NOT NULL DEFAULT '',
  `collation(_utf8'a')` varchar(64) CHARACTER SET utf8 NOT NULL DEFAULT ''
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;
select TRUE,FALSE,NULL;
TRUE	FALSE	NULL
1	0	NULL
create table t1 (c1 char(5)) character set=latin1;
insert into t1 values('row 1');
insert into t1 values('row 2');
insert into t1 values('row 3');
select concat(user(), '--', c1) from t1;
concat(user(), '--', c1)
root@localhost--row 1
root@localhost--row 2
root@localhost--row 3
select concat(database(), '--', c1) from t1;
concat(database(), '--', c1)
test--row 1
test--row 2
test--row 3
drop table t1;
create table t1 (a char(10)) character set latin1;
select * from t1 where a=version();
a
select * from t1 where a=database();
a
select * from t1 where a=user();
a
insert into t1 values ('a');
select left(concat(a,version()),1) from t1;
left(concat(a,version()),1)
a
drop table t1;