create table t1 (USR_ID integer not null, MAX_REQ integer not null, constraint PK_SEA_USER primary key (USR_ID)) engine=InnoDB;
insert into t1 values (1, 3);
select count(*) + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ from t1 group by MAX_REQ;
count(*) + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ + MAX_REQ - MAX_REQ
1
select Case When Count(*) < MAX_REQ Then 1 Else 0 End from t1 where t1.USR_ID = 1 group by MAX_REQ;
Case When Count(*) < MAX_REQ Then 1 Else 0 End
1
drop table t1;
create table t1m (a int) engine=myisam;
create table t1i (a int) engine=innodb;
create table t2m (a int) engine=myisam;
create table t2i (a int) engine=innodb;
insert into t2m values (5);
insert into t2i values (5);
select min(a) from t1m;
min(a)
NULL
select min(7) from t1m;
min(7)
NULL
select min(7) from DUAL;
min(7)
7
explain select min(7) from t2m join t1m;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
select min(7) from t2m join t1m;
min(7)
NULL
select max(a) from t1m;
max(a)
NULL
select max(7) from t1m;
max(7)
NULL
select max(7) from DUAL;
max(7)
7
explain select max(7) from t2m join t1m;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
select max(7) from t2m join t1m;
max(7)
NULL
select 1, min(a) from t1m where a=99;
1	min(a)
1	NULL
select 1, min(a) from t1m where 1=99;
1	min(a)
1	NULL
select 1, min(1) from t1m where a=99;
1	min(1)
1	NULL
select 1, min(1) from t1m where 1=99;
1	min(1)
1	NULL
select 1, max(a) from t1m where a=99;
1	max(a)
1	NULL
select 1, max(a) from t1m where 1=99;
1	max(a)
1	NULL
select 1, max(1) from t1m where a=99;
1	max(1)
1	NULL
select 1, max(1) from t1m where 1=99;
1	max(1)
1	NULL
select min(a) from t1i;
min(a)
NULL
select min(7) from t1i;
min(7)
NULL
select min(7) from DUAL;
min(7)
7
explain select min(7) from t2i join t1i;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	
1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	Using join buffer
select min(7) from t2i join t1i;
min(7)
NULL
select max(a) from t1i;
max(a)
NULL
select max(7) from t1i;
max(7)
NULL
select max(7) from DUAL;
max(7)
7
explain select max(7) from t2i join t1i;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	
1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	Using join buffer
select max(7) from t2i join t1i;
max(7)
NULL
select 1, min(a) from t1i where a=99;
1	min(a)
1	NULL
select 1, min(a) from t1i where 1=99;
1	min(a)
1	NULL
select 1, min(1) from t1i where a=99;
1	min(1)
1	NULL
select 1, min(1) from t1i where 1=99;
1	min(1)
1	NULL
select 1, max(a) from t1i where a=99;
1	max(a)
1	NULL
select 1, max(a) from t1i where 1=99;
1	max(a)
1	NULL
select 1, max(1) from t1i where a=99;
1	max(1)
1	NULL
select 1, max(1) from t1i where 1=99;
1	max(1)
1	NULL
explain select count(*), min(7), max(7) from t1m, t1i;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1m	system	NULL	NULL	NULL	NULL	0	const row not found
1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	
select count(*), min(7), max(7) from t1m, t1i;
count(*)	min(7)	max(7)
0	NULL	NULL
explain select count(*), min(7), max(7) from t1m, t2i;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1m	system	NULL	NULL	NULL	NULL	0	const row not found
1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	
select count(*), min(7), max(7) from t1m, t2i;
count(*)	min(7)	max(7)
0	NULL	NULL
explain select count(*), min(7), max(7) from t2m, t1i;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t2m	system	NULL	NULL	NULL	NULL	1	
1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	
select count(*), min(7), max(7) from t2m, t1i;
count(*)	min(7)	max(7)
0	NULL	NULL
drop table t1m, t1i, t2m, t2i;