Mysql database management commands

Query statements start with select
For example, query the mysql version number
select version() query the current mysql version number
describe table name query table data type
insert into table name values ​​InsertA piece of data
update update data
help help command, which will list some commonly used commands
show databases; query all databases
create database database name; create database
drop database database name; deletedatabase
use database name; enter database
show tables +table name enter table input
show columns from +table name view table properties
show view display extensive server status information
show create database| show create table is used to display the creation of a specific database table and mysql statement respectively
order by +id The field of the order by +id is id The sort order is the order of A-Z, if it is a descending order, you need to add the DESC keyword to DESC onlyWorks on the front face list

Mysql operator

AND, && Logical AND
NOT, ! Negative Value
OR, || Logical OR
XOR Logical Exclusive Or

Mysql database_table management command

create table users; create a table followed by parentheses to set properties
->(id,int primary key, create id and set the primary key
-> name text);
show tables View database tables
drop table users delete the specified database table

Mysql command in use

1.CASCADE: Delete or update from the parent table and automatically delete or update the matching row in the child table.
2.SET NULL: Delete or update rows from the parent table, and set the foreign key column in the child table to NULL.If you use this option, you must ensure that the subtable column does not specify NOT NULL.
3. RESTRICT: Deny delete or update operations on the parent table.
4 NO ACTION: keyword of standard SQL, same as RESTRICT in MySQL.