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select database();
database()
test
select database() = "test";
database() = "test"
1
select user() like "%@%";
user() like "%@%"
#
select version() > "2009.01.756";
version() > "2009.01.756"
1
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 schema() 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()` VARBINARY(136) DEFAULT NULL,
`user()` VARBINARY(308) DEFAULT NULL,
`version` VARCHAR(60) COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=DEFAULT COLLATE = utf8_general_ci
drop table t1;
select TRUE,FALSE,NULL;
TRUE FALSE NULL
1 0 NULL
create table t1 (c1 char(5));
insert into t1 values('row 1');
insert into t1 values('row 2');
insert into t1 values('row 3');
select concat(SUBSTRING(user(), 0, 4), '--', c1) from t1;
concat(SUBSTRING(user(), 0, 4), '--', c1)
--row 1
--row 2
--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));
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;
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