1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
create table cm.tb_user(
id int,
name varchar(255),
age int,
gender varchar(16)
);
create table cm.tb_user(
id int primary key,
name varchar(255),
age int,
gender varchar(16),
store_time datetime default now()
);
create table cm.tb_user(
id int primary key ,
name varchar(255) not null default 'NULL',
age int,
gender varchar(16),
create_time datetime default now(),
update_time datetime default now()
);
create table cm.tb_user(
id int primary key ,
name varchar(255) not null default '-',
age int,
gender varchar(16),
store_time datetime default now(),
update_time datetime default now()
);
select min(age), max(age) from cm.tb_user where age < 40 group by gender;
select
min(age),
max(age)
from cm.tb_user
where age < 40
group by gender;
select id,
name
from cm.tb_user
where age > 10
and id<=10010;
select id,
name
from cm.tb_user
where 1=1
and age > 10
and id<=10010;
insert into cm.tb_user
values
(1001, 'Mike', 20, 'M');
insert into cm.tb_user
(id, name, age, gender)
values
(1001, 'Mike', 20, 'M');
explain
select *
from cm.tb_user
where id=1001 and age = 20;
select *
from cm.tb_user;
select id,
name
from cm.tb_user;
delete
from cm.tb_user
where age > 35
limit 5;
delete from cm.tb_user
where age <= 20;
update cm.tb_user
set age = age + 1;
begin;
delete from cm.tb_user
where age <= 20;
update cm.tb_user
set age = age + 1;
commit;
insert into cm.data_count
(dt, count)
values
('2023-06-20', 101),
('2023-06-21', 231),
('2023-06-22', 170),
('2023-06-23', 146),
('2023-06-24', 187),
('2023-06-25', 123),
('2023-06-26', 221),
('2023-06-27', 101),
('2023-06-28', 103),
('2023-06-29', 122),
('2023-06-30', 144);
select dt, count
from cm.data_count t1;
select
t1.dt,
t1.count * 1.0 / t2.count as ratio
from cm.data_count t1
join cm.data_count t2
on datediff(t1.dt, t2.dt)=7;
|