MySQL...

show databases;

create database [db_name];

use [db_name];

drop database [db_name];

create table [table_name] (col1,col2,col3....col)

ex: create table tb1 (id int(11) primary key, name varchar(20) not null, city varchar(15);

show tables;

desc [table_name];

drop table [table_name];

alter table [table_name] rename to [new_table_name];

truncate table [table_name];

insert into [table_name] (id,name,city) values(1,'aks','delhi');

insert into [table_name] values (1,'aks','delhi');

select * from [table_name];

alter table [table_name] add [column_name];

update [table_name] set [column_name] = [value] where id = [value];

delete from [table_name] where id=1; #delete row

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select * from [table_name] where [column_name = -----];

select e_name, city,salary from [table_name] where [column_name = -----];

select e_name as 'USERNAME', city as 'CITYNAME' from [table_name];

select distinct([column_name]) from [table_name];---------different values

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select * from [table_name] where [column_name = --] and [column_name = --];

select * from [table_name] where [column_name >= --] and [column_name <= --];

select * from [table_name] where [column_name] between -----;

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select * from [table_name] where [column_name = --] or [column_name = --];

select * from [table_name] where [column_name] in ([]);

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select * from [table_name] limit [value];----show from top

select * from [table_name] limit [value] offset [value];

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select * from [table_name] order by [column_name] desc;

select * from [table_name] order by [column_name] desc limit 2;

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LIKE

% = 0,1 or multiple charecter

_ = single charecter

select * from [table_name] where [column_name] like 'a%';

select * from [table_name] where [column_name] like '_a%';

select * from [table_name] where [column_name] like '%a_';

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FUNC =SUM, AVG, MIN, MAX

select SUM([column_name]) from [table_name];

select SUM([column_name]) as 'ALIAS' from [table_name];

select [value] from [table] where column = (select MIN([column]) from [table];

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Foreign key is used to interconnet table.

create table [table] (col1, col2, col3, foreign key(col) references [table](col);