In Star schema, the Fact is at the center and surrounded by dimension tables. A snowflake schema is similar to star schema. In Snowflake schema, dimension table/s may be connected to other related dimensions. For example, the Product dimension may connect to the Category dimension.
A primary key uniquely identifies a record in a table. The primary key in one table is referenced by a foreign key in another table. Two relational tables are linked based on the primary key and foreign key.
a) Inner Join. Returns matching rows from both the tables.
b) Left/Outer join. Returns all rows from the left table and the matched rows from the right table.
c) Right/Outer join. Returns all rows from the Right table and the matched rows from the left table.
d) Full/Outer join. Returns all rows from table1 and from the table. It combines the result of both LEFT and RIGHT joins.
e) Cartesian join. Join every row of one table to every row of another table.