What is a join in T SQL and Different Types of Joins

In T-SQL, a join is used to combine rows from two or more tables based on a related column between them. This helps to retrieve data from multiple tables in a single query.

Types of Joins in T SQL:

1. INNER JOIN: Retrieves rows that have matching values in both tables.
2. LEFT JOIN (or LEFT OUTER JOIN): Retrieves all rows from the left table and the matched rows from the right table.
3. RIGHT JOIN (or RIGHT OUTER JOIN): Retrieves all rows from the right table and the matched rows from the left table.
4. FULL JOIN (or FULL OUTER JOIN): Retrieves rows when there is a match in one of the tables.
5. CROSS JOIN: Returns the Cartesian product of the two tables.

Understanding and effectively utilizing different types of joins in T-SQL is crucial for querying data from multiple tables efficiently.