mysql

create database if not exists database_name;

show databases;

use database_name;

drop database if exists database_name;

create table table_name(

column_name data_type(size) [NOT] NULL,

.

primary key(col_name)

);

show tables;

describe table_name;

drop table table_name;

truncate table table_name;

alter table table_name 

select column_name1,column_name2,...

from tables

[where condition="conditions"]

[group BY group

[having group_conditions]]

[order BY sort_columns]

[limit limits];

select distinct column_name from tables;

select count(*), column_name from table_name group by column_name;

select count(*), column_name from table_name group by column_name having count(*)=1;

select column1,column2 from table_name order by column1 asc, column2 desc;

select column1,column2 from table_name where column1like' '

select column1,column2 from table_name1 union select column1,column2 from table_name2