第五节课小结

SQL (Structured Query Language)

Relational model, 关系模型.

可以 read、modify 和 learn.

Create 建立 model:

CREATE TABLE tbl{
	a INT,
	b CHAR(n),
	KEY (a)
}

Select, From, Where, Delete, Order By

SELECT / DELETE _
FROM _
WHERE _ AND / OR / NOT
ORDER BY _

Join, Union, Intersect, Count, Group By

_ UNION _