Temporary tables in SQL are a powerful feature that allows users to store and manipulate intermediate result sets within a session. They are particularly useful for complex queries, data manipulation, and temporary storage needs. Let's delve into the types of temporary tables and their common use cases:
Types of Temporary Tables:
1- Local Temporary Tables (#tableName):
- Local temporary tables are only visible within the current session.
- They are automatically dropped when the session ends or when the connection is closed.
- Example of creating a local temporary table:
CREATE TABLE #TempTable (
ID INT,
Name VARCHAR(50)
);
2- Global Temporary Tables (##tableName):
- Global temporary tables are visible to all sessions.
- They are dropped when the last session using the table is closed.
- Example of creating a global temporary table:
CREATE TABLE ##TempTable (
ID INT,
Name VARCHAR(50)
);
Common Use Cases for Temporary Tables:
1- Storing Intermediate Results:
- Temporary tables are often used to store intermediate results of complex queries to improve performance and simplify logic.
2- Data Transformation:
- Temporary tables can be used to transform data before inserting it into permanent tables.
3- Session-Specific Data:
- Local temporary tables are useful for storing session-specific data that should not be shared across sessions.
4- Temporary Storage:
- Temporary tables can act as temporary storage for data that needs to be processed or manipulated before final storage.
you can also use drop query to drop it. Like drop table #tablename or ##tablename
In conclusion, understanding the types and use cases of temporary tables in SQL can greatly enhance your ability to manage and manipulate data effectively within your database sessions.