drop table if exists t1,t2;
create table t1 (pk int primary key, grp int, a int, c char(10) not null);
insert into t1 values (1, 1,1,'a');
insert into t1 values (2, 2,2,'b');
insert into t1 values (3, 2,3,'c');
insert into t1 values (4, 3,4,'E');
insert into t1 values (5, 3,5,'C');
insert into t1 values (6, 3,6,'D');
select a,c,sum(a) from t1 group by a order by a;
a	c	sum(a)
1	a	1
2	b	2
3	c	3
4	E	4
5	C	5
6	D	6
select a,c,sum(a) from t1 where a > 10 group by a order by a;
a	c	sum(a)
select sum(a) from t1 where a > 10;
sum(a)
NULL
select count(distinct a),count(distinct grp) from t1;
count(distinct a)	count(distinct grp)
6	3
insert into t1 values (7, null,null,'');
select count(distinct a),count(distinct grp) from t1;
count(distinct a)	count(distinct grp)
6	3
create table t2 (pk int primary key, grp int, a int, c char(10));
select grp,max(a)+max(grp),max(c) from t1 group by grp order by grp;
grp	max(a)+max(grp)	max(c)
NULL	NULL	
1	2	a
2	5	c
3	9	E
select * from t2;
pk	grp	a	c
drop table t1,t2;
drop table if exists t1;
CREATE TABLE t1 (id int ,value1 decimal(10,2),c int primary key);
INSERT INTO t1 VALUES (1,0.00,1),(1,1.00,2), (1,2.00,3), (2,10.00,4), (2,11.00,5), (2,12.00,6);
CREATE TABLE t2 (id int primary key,name char(20));
INSERT INTO t2 VALUES (1,'Set One'),(2,'Set Two');
select id, avg(value1)  from t1 group by id;
id	avg(value1)
1	1.000000
2	11.000000
select name, avg(value1) from t1, t2 where t1.id = t2.id group by t1.id;
name	avg(value1)
Set One	1.000000
Set Two	11.000000
drop table t1,t2;
create table t1 (pk int primary key, id int not null);
create table t2 (pk int primary key, id int not null,rating int null);
insert into t1 values(1,1),(2,2),(3,3);
insert into t2 values(1, 1, 3),(2, 2, NULL),(3, 2, NULL),(4, 3, 2),(5, 3, NULL);
select t1.id, avg(rating) from t1 left join t2 on ( t1.id = t2.id ) group by t1.id order by t1.id;
id	avg(rating)
1	3.0000
2	NULL
3	2.0000
drop table t1,t2;
create table t1 (a int primary key, c char(10), b char(128));
INSERT INTO t1 VALUES (1,'1','1');
INSERT INTO t1 VALUES (2,'2','2');
INSERT INTO t1 VALUES (4,'4','4');
select count(*) from t1;
count(*)
3
select count(*) from t1 where a = 1;
count(*)
1
select count(*) from t1 where a = 100;
count(*)
0
select count(*) from t1 where a >= 10;
count(*)
0
select count(a) from t1 where a = 1;
count(a)
1
select count(a) from t1 where a = 100;
count(a)
0
select count(a) from t1 where a >= 10;
count(a)
0
select count(b) from t1 where b >= 2;
count(b)
2
select count(b) from t1 where b >= 10;
count(b)
0
select count(c) from t1 where c = 10;
count(c)
0
drop table t1;
CREATE TABLE t1 (d datetime default now(), i int primary key);
INSERT INTO t1(i) VALUES (1);
SELECT COUNT(i), i, COUNT(i)*i FROM t1 GROUP BY i;
COUNT(i)	i	COUNT(i)*i
1	1	1
SELECT COUNT(i), (i+0), COUNT(i)*(i+0) FROM t1 GROUP BY i;
COUNT(i)	(i+0)	COUNT(i)*(i+0)
1	1	1
DROP TABLE t1;
create table t1 (
pk int primary key,
num float,
my_user char(20)
);
insert into t1 values (1, 10.3,'nem'),(2, 20.53,'monty'),(3, 30.23,'sinisa');
insert into t1 values (4, 30.13,'nem'),(5, 20.98,'monty'),(6, 10.45,'sinisa');
insert into t1 values (7, 5.2,'nem'),(8, 8.64,'monty'),(9, 11.12,'sinisa');
select sum(num) from t1;
sum(num)
147.57999897003174
select sum(num) from t1 group by my_user order by my_user;
sum(num)
50.15000057220459
45.6299991607666
51.79999923706055
drop table t1;
drop table if exists t1,t2,t3;
create table t1 (pk int primary key, a1 int, a2 char(3));
insert into t1 values(1, 10,'aaa'), (2, 10,null), (3, 10,'bbb'), (4, 20,'zzz');
create table t2(pk int primary key, a1 char(3), a2 int, a3 float);
create table t3(pk int primary key, a1 char(3), a2 int, a3 float);
select * from t1;
pk	a1	a2
1	10	aaa
2	10	NULL
3	10	bbb
4	20	zzz
select min(a2) from t1;
min(a2)
aaa
select max(t1.a1), max(t2.a2) from t1, t2;
max(t1.a1)	max(t2.a2)
NULL	NULL
insert into t2 values(1, 'AAA', 10, 0.5);
insert into t2 values(2, 'BBB', 20, 1.0);
select t1.a1, t1.a2, t2.a1, t2.a2 from t1 left outer join t3 on t1.a1=10;
ERROR 42S22: Unknown column 't2.a1' in 'field list'
select max(t1.a2) from t1 left outer join t2 on t1.a1=10;
max(t1.a2)
zzz
select max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk and 1=0 where t2.a1='AAA';
max(t2.a1)
NULL
explain select max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk and 1=0 where t2.a1='AAA';
select max(t2.a1) from t1 left outer join t2 on t1.a2=t2.a1   where t2.a1='AAA';
max(t2.a1)
AAA
explain select max(t2.a1) from t1 left outer join t2 on t1.a2=t2.a1  where t2.a1='AAA';
select max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk   where t2.a1='AAA' and 1=0;
max(t2.a1)
NULL
explain select max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk  where t2.a1='AAA' and 1=0;
select max(t1.a2),max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk and t1.a1=10;
max(t1.a2)	max(t2.a1)
zzz	BBB
explain select max(t1.a2),max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk and t1.a1=10;
select max(t1.a2),max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk and t1.pk=10;
max(t1.a2)	max(t2.a1)
zzz	NULL
explain select max(t1.a2),max(t2.a1) from t1 left outer join t2 on t1.pk=t2.pk and t1.pk=10;
select * from t1 left join t2 on t1.pk=t2.pk where t2.a2 > 1 and t2.a2 < 10;
pk	a1	a2	pk	a1	a2	a3
explain select * from t1 left join t2 on t1.pk=t2.pk where t2.a2 > 1 and t2.a2 < 10;
select * from t1 left join t2 on t1.pk=t2.pk and t2.a2 > 1 and t2.a2 < 10 order by t1.pk;
pk	a1	a2	pk	a1	a2	a3
1	10	aaa	NULL	NULL	NULL	NULL
2	10	NULL	NULL	NULL	NULL	NULL
3	10	bbb	NULL	NULL	NULL	NULL
4	20	zzz	NULL	NULL	NULL	NULL
explain select * from t1 left join t2 on t1.pk=t2.pk and t2.a2 > 1 and t2.a2 < 10;
drop table t1,t2;
CREATE TABLE t1 (pk int primary key, a int, b int);
select count(b), sum(b), avg(b),  min(b), max(b) from t1;
count(b)	sum(b)	avg(b)	min(b)	max(b)
0	NULL	NULL	NULL	NULL
select a,count(b), sum(b), avg(b), min(b), max(b) from t1 group by a order by a;
a	count(b)	sum(b)	avg(b)	min(b)	max(b)
insert into t1 values (1, 1,null);
select a,count(b), sum(b), avg(b), min(b), max(b) from t1 group by a order by a;
a	count(b)	sum(b)	avg(b)	min(b)	max(b)
1	0	NULL	NULL	NULL	NULL
insert into t1 values (2, 1,null);
insert into t1 values (3, 2,null);
select a,count(b), sum(b), avg(b), min(b), max(b) from t1 group by a order by a;
a	count(b)	sum(b)	avg(b)	min(b)	max(b)
1	0	NULL	NULL	NULL	NULL
2	0	NULL	NULL	NULL	NULL
insert into t1 values (4, 2,1);
select a,count(b), sum(b), avg(b), min(b), max(b) from t1 group by a order by a;
a	count(b)	sum(b)	avg(b)	min(b)	max(b)
1	0	NULL	NULL	NULL	NULL
2	1	1	1.0000	1	1
insert into t1 values (5, 3,1);
select a,count(b), sum(b), avg(b), min(b), max(b) from t1 group by a order by a;
a	count(b)	sum(b)	avg(b)	min(b)	max(b)
1	0	NULL	NULL	NULL	NULL
2	1	1	1.0000	1	1
3	1	1	1.0000	1	1
drop table t1;
create table t1 (col int primary key,col2 int);
insert into t1(col) values (-1), (-2), (-3);
drop table t1;
create table t1 (a int primary key,b int);
select avg(2) from t1;
avg(2)
NULL
drop table t1;