1.insert

insert into 表名(字段1, 字段2) values(值1, 值2);

2.update

UPDATE table_name SET field1=new-value1, field2=new-value2
[WHERE Clause]

3.select

SELECT 
	column_name,
	column_name
FROM 
	table_name
[WHERE Clause]
[LIMIT N][ OFFSET M]

4.delete

DELETE FROM table_name [WHERE Clause]