SQL statement 1

SQL statement 1
Use data

Use mydata;

Create a table
Create table longmao
(
Depeno int primary key,
Dname varchar (20 ),
Loc varchar (20)

);

Insert data to the table

Inseert into toroto values (1, 'feifei ');

Show all tables

Show tables;

Show table data

Select * from toroto;

Left join

Select * from t1 left join t2 on t1.id = t2.id;

Right join

Select * from t1 right join t2 on t1.id = t2.id;

Show all databases

Show databases;

Display table structure

Desc toroto;

Select a row from row 3rd

Select * from toroto order by id desc limit 3, 1;

Delete table data

Delete from toroto;

Delete table

Drop table toroto;

Auto_increment
Create table toroto
(
Id int primary key auto_increment,
Name varchar (20)
);
Null

Insert into toroto values (null, 'pangpang1 ');

Insert only the name Element

Insert into toroto (name) values ('pangpang3 ');

Show current time

Select now ();

Add a home column after name

Alter table toroto add home varchar (100) after name;

Delete the home field

Alter table toroto drop home;

Replace the name with 1 with baobao

Update toroto set name = 'Bao' where id = '1 ';

Select the data with the same id in the two tables.

Select * from toroto, toroto2 where toroto. id = toroto2.id;

Select data with id = 2 in the table
Select * from toroto where id = 2;