最简单的sql语法

【select】

SELECT select_list

[INTO new_table]

FROM table_source

[WHERE search_condition]

[GROUP BY group_by_expression]

[HAVING search_condition]

[ORDER BY order_expression[ ASC | DESC ]]

• select demo

select * from persons where (firstname="" or firstname="") and lastname="";

select * from persons where lastname [not] between "" and "";

select distinct lastname from persons;

select lastname from persons order by lastname [ASC | DESC];

select company, sum(amount) from sales group by company;

select company, sum(amount) from sales group by company having sum(amount)>10000;

select count(column_name) from table_name;// sum, avg, max, min, abs, ceil, floor, cos, ...

• 关于join

select employees.name, orders.product from employees, orders where employees.id=orders.id;

select employees.name, orders.product from employees inner join orders on employees.id=orders.id;

• 取别名

select column as column_alias from table;

select column from table as table_alias;

【insert】

insert into table_name values (value1, value2, ...);

insert into table_name (column1, column2, ...) values (value1, value2, ...);

【update】

update person set firstname='', middlename='' where lastname='';

【delete】

delete from table_name where lastname='';

【create】

create table table_name (column1 data_type, column2 data_type);

【alter】

alter table table_name add columni datatype;

alter table table_name drop column column_name;

【drop】

drop table table_name;

【create db】

create database database_name;

【drop db】

drop database database_name;