What are temporary tables in SQL Server?

Temporary tables in SQL Server are a special type of table used to store temporary data. They are automatically destroyed when the session ends or when the user actively deletes them, and do not persist in the database long-term. Temporary tables are often used to store intermediate results or temporary data for complex queries or data processing. In SQL Server, temporary tables can be created in two ways.

1. Global temporary tables are created by adding the “##” prefix before the table name, such as “##tempTable”. These tables are only destroyed when the session that created them ends.
2. Local temporary table: When creating a temporary table, add a “#” prefix before the table name, for example “#tempTable”. Local temporary tables are only destroyed when the session or stored procedure that created them ends.

Utilizing temporary tables can enhance query performance and simplify complex query operations, but it is important to consider the scope and lifespan of these tables to avoid data confusion or storage space wastage.