Simple command of mysql

Database words

create create
database database
drop delete
show show
use use
delete delete
describe describe desc
select query
varchar stringtype
char string type
date date
time time
datetime time date

Statement
createa database; library name; create library
drop database; library name; delete library
show databases; view all libraries
use library name; use library
desc table name;Query table structure
desc table name header;query a structure

Create table basic structure

create table table name (
                                             ;

Modify structure

1. Add fields add
Add one field at a time
Alter table table name add field name field type;
Add multiple fields at a time
Alter table table name add field name fieldtype, add field name field type,...;

2 delete fields drop
delete one field at a time
alter table table name drop field name field type;
delete multiple fields at a time
alter table table name drop field name field type, drop field name field type,...;

3 Modify field type modify
Modify one field at a time
Alter table table name modify field name modify field type;
Modify multiple fields at a time
Alter table table name modify field nameModify field type, modify field name modify field type...;

4 Modify field name change
Modify one field name at a time
Alter table table name change Original field name modified field name Modified field type;
Modify multiple field names at a time
Alter table table name change original field name modified field name modified field type, change original field name modified field name modified field type...;

Deletion of data table

1 delete table
drop table table name;
2 modify table name
1) rename table original table name to new table name;
2) alter table original table name renameto new table name;

Data Insertion

1. Add one at a time
Insert into table name (column name 1, column name 2, column name 3) value (data 1, data 2, data 3);
2. Add at a timeMultiple
insert into table name (column name 1, column name 2, column name 3) value
(data 1, data 2, data 3),
(data 1, data 2, data 3),
(Data1,Data2,Data3),
(…);

Query table content
Select * from table name;
Query single data
Select field from table name;
Query multiple data
select field name 1, field name 2, fieldname 3 from table name;
deduplication query
selest distinct field name from table name;
operator query
select field name + field name from table name;
conditional query result in 80The above
select name, score from table name where score>80;
set query
1 in the range of set query
select * from table name where field name in();
2Not in collection range query
Select * from table name where field name not in();
Range query
Select * from table name where field name between 70 and 90;
Null value query
select field name from table name where score is empty in null;
non-null value query
select field name from table name where score in not null;
multi-condition query
select * from table name whereGrade>80 and age>15;
Add primary key constraint
Alter table table name add primarg key (field name);
Delete self-increment constraint/primary key constraint
Alter table table name modify field name fieldtype;
alter table table name drop primarg key;
delete not-null constraint
alter table table name modify field name field type;
delete unique constraint
alter table table name modify field name fieldtype;
alter table table name drop index field name;
delete default constraint
alter table table name modify field name field type;
default default

primary key constraint primarg key

Auto Increment Constraint auto_increment

Foreign key constraints
 foreign key (field name) references table name (field name);
delete foreign key
  alter table table name drop foreign key name;

Name the foreign key constyaint name

sort in descending order
select * from table name order by field desc;
ascending order
select * from table name order by field asc;

Modify the fields of a single record
 update table name set field name='modified name'where id=1;

Modify fields of multiple records
Update table name set field name='modified name'  … where id=serial number;

Data deletion
delete a record
delete from table name where id=1;
delete multiple records
delete from table name where id=2 or id=3;