Types of Joins in Sql Server 2005
First of all take a look on the names of different types of joins in SQL.
- Inner Join
- Outer Join
- Left Outer Join
- Right Outer Join
- Full Outer Join
Joins in SQL Server allows the retrieval of data records from one or more tables having some relation between them. Logical operators can also be used to drill down the number of records to get the desired output from sql join queries.
1. Inner Join
Inner Join is a default type join of SQL Server. It uses logical operators such as =, <, > to match the records in two tables. Inner Join includes equi join and natural joins.
2. Outer Join
Outer Join has further 3 sub categories as left, right and full. Outer Join uses these category names as keywords that can be specified in the FROM clause.
2.1 Left Outer Join
Left Outer Join returns all the rows from the table specified first in the Left Outer Join Clause. If in the left table any row has no matching record in the right side table then that row returns null column values for that particular tuple.
2.2 Right Outer Join
Right Outer Join is exactly the reverse method of Left Outer Join. It returns all the rows from right table and returns null values for the rows having no match in the left joined table.
2.3 Full Outer Join
Full outer join returns all the rows from both left and right joined tables. If there is any match missing from the left table then it returns null column values for left side table and if there is any match missing from right table then it returns null value columns for the right side table.
3. Cross Join
Cross join works as a Cartesian product of rows for both left and right table. It combined each row of left table with all the rows of right table.
Other SQL Join Examples
Also read the tutorial: Self Join In Sql Server 2000 2005 to learn how to apply the self join to the sql server table to fetch the inter-related data from a single table.