DROP TABLE IF EXISTS t;
CREATE TABLE t (
c1 int,
c2 int,
c3 int,
PRIMARY KEY (c1)
);
INSERT INTO t VALUES (1,2,3);
SELECT * from t;
c1	c2	c3
1	2	3
SELECT c1, c2, c3 from t;
c1	c2	c3
1	2	3
SELECT c1, c1 from t;
c1	c1
1	1
SELECT c1 as a, c2 as a from t;
a	a
1	2
SELECT 1;
1
1
SELECT 1, 1;
1	1
1	1
SET @@autocommit = 1;
SELECT @@autocommit;
@@autocommit
1
SELECT @@autocommit, @@autocommit;
@@autocommit	@@autocommit
1	1
SET @a = 10;
SET @b = 11;
SELECT @a, @@autocommit;
@a	@@autocommit
10	1
SELECT @a, @b;
@a	@b
10	11
SELECT 1, @a;
1	@a
1	10
SELECT 1, @a as a;
1	a
1	10
SELECT 1, @a, @@autocommit as a, c1 from t;
1	@a	a	c1
1	10	1	1
SET @b = "123";
SELECT @b + "123";
@b + "123"
246
SELECT 1 + 1;
1 + 1
2
SELECT 1 a, 1 as a, 1 + 1 a;
a	a	a
1	1	2
SELECT c1 a, c1 as a from t;
a	a
1	1
SELECT * from t LIMIT 0,1;
c1	c2	c3
1	2	3
SELECT * from t LIMIT 1;
c1	c2	c3
1	2	3
SELECT * from t LIMIT 1,1;
c1	c2	c3
SELECT * from t LIMIT 1 OFFSET 0;
c1	c2	c3
1	2	3
DROP TABLE IF EXISTS t2;
CREATE TABLE t2 (
c1 int,
c2 int,
PRIMARY KEY (c1)
);
INSERT INTO t2 VALUES (1,2);
SELECT * from t a;
c1	c2	c3
1	2	3
SELECT * from t a, t2 b;
c1	c2	c3	c1	c2
1	2	3	1	2
SELECT * from t as a, t2 as b;
c1	c2	c3	c1	c2
1	2	3	1	2
SELECT * from t a left join t2 b on a.c1 = b.c1;
c1	c2	c3	c1	c2
1	2	3	1	2
SELECT * from (SELECT 1, 1) as a;
Error 1060: Duplicate column name '1'
SELECT * from (SELECT * FROM t, t2) as a;
Error 1060: Duplicate column name 'c1'
DROP TABLE IF EXISTS t;
CREATE TABLE t (c1 INT, c2 INT);
INSERT INTO t VALUES (1, 2), (1, 1), (1, 3);
SELECT c1=c2 FROM t;
c1=c2
0
1
0
SELECT 1=1;
1=1
1
SELECT t.c1 + t.c2 from t limit 1;
t.c1 + t.c2
3
SELECT t.c1 from t limit 1;
c1
1
SELECT t.c1 + c2 from t limit 1;
t.c1 + c2
3
SELECT c1 + 10 from t limit 1;
c1 + 10
11
SELECT t.c1 + 10 from t limit 1;
t.c1 + 10
11
SELECT all c1, c2 from t limit 1;
c1	c2
1	2
SELECT distinct c1, c2 from t order by c1, c2 limit 1;
c1	c2
1	1
SELECT c2 from t where not (c2 > 2);
c2
2
1
select c2 from t where not null is null;
c2
select !(1 + 2);
!(1 + 2)
0
select + - 1, --1, +-+-+1, + "123";
+ - 1	--1	+-+-+1	+ "123"
-1	1	1	123
select --------------------1, ++++++++++++++++++++1;
--------------------1	++++++++++++++++++++1
1	1
select --+(1 + 1), +-+-(1 * 1);
--+(1 + 1)	+-+-(1 * 1)
2	1
select * from t where null;
c1	c2
select * from t where 1;
c1	c2
1	2
1	1
1	3
select * from t where 0;
c1	c2
select * from t where 0 * 10;
c1	c2
select * from t where null is not null;
c1	c2
select * from t where !1;
c1	c2
select * from t where 1 && 0 || 3 && null;
c1	c2
select * from t as a, t2 as b;
c1	c2	c1	c2
1	2	1	2
1	1	1	2
1	3	1	2
select * from t as a cross join t2 as b;
c1	c2	c1	c2
1	2	1	2
1	1	1	2
1	3	1	2
select * from t as a join t2 as b;
c1	c2	c1	c2
1	2	1	2
1	1	1	2
1	3	1	2
select * from t as a join t2 as b on a.c2 = b.c2;
c1	c2	c1	c2
1	2	1	2
select * from (t);
c1	c2
1	2
1	1
1	3
select * from (t as a, t2 as b);
c1	c2	c1	c2
1	2	1	2
1	1	1	2
1	3	1	2
select * from (t as a cross join t2 as b);
c1	c2	c1	c2
1	2	1	2
1	1	1	2
1	3	1	2
select 1 as a from t;
a
1
1
1
select count(*), 1 from t;
count(*)	1
3	1
select *, 1 from t;
c1	c2	1
1	2	1
1	1	1
1	3	1
select 1, count(1), sum(1);
1	count(1)	sum(1)
1	1	1
drop table if exists t1;
create table t1(a int primary key, b int, c int, index idx(b, c));
insert into t1 values(1, 2, 3);
insert into t1 values(2, 3, 4);
insert into t1 values(3 ,4, 5);
insert into t1 values(4, 5, 6);
insert into t1 values(5, 6, 7);
insert into t1 values(6, 7, 8);
insert into t1 values(7, 8, 9);
insert into t1 values(9, 10, 11);
explain select a, c from t1 use index(idx) order by a limit 5;
id	count	task	operator info
TopN_7	5.00	root	test.t1.a:asc, offset:0, count:5
└─IndexReader_15	5.00	root	index:TopN_14
  └─TopN_14	5.00	cop	test.t1.a:asc, offset:0, count:5
    └─IndexScan_13	10000.00	cop	table:t1, index:b, c, range:[NULL,+inf], keep order:false, stats:pseudo
select c, a from t1 use index(idx) order by a limit 5;
c	a
3	1
4	2
5	3
6	4
7	5
drop table if exists t;
create table t (a int, b int, c int, key idx(a, b, c));
explain select count(a) from t;
id	count	task	operator info
StreamAgg_16	1.00	root	funcs:count(col_0)
└─TableReader_17	1.00	root	data:StreamAgg_8
  └─StreamAgg_8	1.00	cop	funcs:count(test.t.a)
    └─TableScan_15	10000.00	cop	table:t, range:[-inf,+inf], keep order:false, stats:pseudo
select count(a) from t;
count(a)
0
insert t values(0,0,0);
explain select distinct b from t group by a;
id	count	task	operator info
HashAgg_7	8000.00	root	group by:test.t.b, funcs:firstrow(test.t.b)
└─StreamAgg_20	8000.00	root	group by:col_1, funcs:firstrow(col_0)
  └─IndexReader_21	8000.00	root	index:StreamAgg_11
    └─StreamAgg_11	8000.00	cop	group by:test.t.a, funcs:firstrow(test.t.b)
      └─IndexScan_19	10000.00	cop	table:t, index:a, b, c, range:[NULL,+inf], keep order:true, stats:pseudo
select distinct b from t group by a;
b
0
explain select count(b) from t group by a;
id	count	task	operator info
StreamAgg_17	8000.00	root	group by:col_1, funcs:count(col_0)
└─IndexReader_18	8000.00	root	index:StreamAgg_8
  └─StreamAgg_8	8000.00	cop	group by:test.t.a, funcs:count(test.t.b)
    └─IndexScan_16	10000.00	cop	table:t, index:a, b, c, range:[NULL,+inf], keep order:true, stats:pseudo
select count(b) from t group by a;
count(b)
1
insert t values(1,1,1),(3,3,6),(3,2,5),(2,1,4),(1,1,3),(1,1,2);
explain select count(a) from t where b>0 group by a, b;
id	count	task	operator info
StreamAgg_21	2666.67	root	group by:col_1, col_2, funcs:count(col_0)
└─IndexReader_22	2666.67	root	index:StreamAgg_9
  └─StreamAgg_9	2666.67	cop	group by:test.t.a, test.t.b, funcs:count(test.t.a)
    └─Selection_20	3333.33	cop	gt(test.t.b, 0)
      └─IndexScan_19	10000.00	cop	table:t, index:a, b, c, range:[NULL,+inf], keep order:true, stats:pseudo
select count(a) from t where b>0 group by a, b;
count(a)
3
1
1
1
explain select count(a) from t where b>0 group by a, b order by a;
id	count	task	operator info
Projection_7	2666.67	root	count(a)
└─StreamAgg_33	2666.67	root	group by:col_2, col_3, funcs:count(col_0), firstrow(col_1)
  └─IndexReader_34	2666.67	root	index:StreamAgg_31
    └─StreamAgg_31	2666.67	cop	group by:test.t.a, test.t.b, funcs:count(test.t.a), firstrow(test.t.a)
      └─Selection_24	3333.33	cop	gt(test.t.b, 0)
        └─IndexScan_23	10000.00	cop	table:t, index:a, b, c, range:[NULL,+inf], keep order:true, stats:pseudo
select count(a) from t where b>0 group by a, b order by a;
count(a)
3
1
1
1
explain select count(a) from t where b>0 group by a, b order by a limit 1;
id	count	task	operator info
Projection_9	1.00	root	count(a)
└─Limit_15	1.00	root	offset:0, count:1
  └─StreamAgg_42	1.00	root	group by:col_2, col_3, funcs:count(col_0), firstrow(col_1)
    └─IndexReader_43	1.00	root	index:StreamAgg_37
      └─StreamAgg_37	1.00	cop	group by:test.t.a, test.t.b, funcs:count(test.t.a), firstrow(test.t.a)
        └─Selection_41	1.25	cop	gt(test.t.b, 0)
          └─IndexScan_40	3.75	cop	table:t, index:a, b, c, range:[NULL,+inf], keep order:true, stats:pseudo
select count(a) from t where b>0 group by a, b order by a limit 1;
count(a)
3
drop table if exists t;
create table t (id int primary key, a int, b int);
explain select * from (t t1 left join t t2 on t1.a = t2.a) left join (t t3 left join t t4 on t3.a = t4.a) on t2.b = 1;
id	count	task	operator info
HashLeftJoin_10	156250000.00	root	left outer join, inner:HashLeftJoin_16, left cond:[eq(t2.b, 1)]
├─HashLeftJoin_11	12500.00	root	left outer join, inner:TableReader_15, equal:[eq(t1.a, t2.a)]
│ ├─TableReader_13	10000.00	root	data:TableScan_12
│ │ └─TableScan_12	10000.00	cop	table:t1, range:[-inf,+inf], keep order:false, stats:pseudo
│ └─TableReader_15	10000.00	root	data:TableScan_14
│   └─TableScan_14	10000.00	cop	table:t2, range:[-inf,+inf], keep order:false, stats:pseudo
└─HashLeftJoin_16	12500.00	root	left outer join, inner:TableReader_20, equal:[eq(t3.a, t4.a)]
  ├─TableReader_18	10000.00	root	data:TableScan_17
  │ └─TableScan_17	10000.00	cop	table:t3, range:[-inf,+inf], keep order:false, stats:pseudo
  └─TableReader_20	10000.00	root	data:TableScan_19
    └─TableScan_19	10000.00	cop	table:t4, range:[-inf,+inf], keep order:false, stats:pseudo
drop table if exists t;
create table t(a bigint primary key, b bigint);
desc select * from t where a = 1;
id	count	task	operator info
Point_Get_1	1.00	root	table:t, handle:1
desc select * from t where a = '1';
id	count	task	operator info
Point_Get_1	1.00	root	table:t, handle:1
desc select sysdate(), sleep(1), sysdate();
id	count	task	operator info
Projection_3	1.00	root	sysdate(), sleep(1), sysdate()
└─TableDual_4	1.00	root	rows:1