Sql based ques. : What is join and there types? What is foreign key?

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Join is used to combine rows from two or more tables based on a related column. Foreign key is a column that refers to the primary key of another table.

Join types: Inner join, Left join, Right join, Full outer join, Cross join
Inner join returns only the matching rows from both tables
Left join returns all the rows from the left table and matching rows from the right table
Right join returns all the rows from the right table and matching rows from the left table
Full outer join returns all the rows from both tables
Cross join returns the Cartesian product of both tables
Foreign key is used to establish a relationship between two tables
Foreign key column in one table refers to the primary key column in another table

Sql based ques. : What is join and there types? What is foreign key?

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