Create Temp Table SQL

How do you create a temporary table in SQL?

Temporary tables are tables that exist only for the duration of a specific session or transaction. They are useful for storing intermediate results or data needed for a specific task. They are automatically dropped when the session ends.

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Description

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Temporary tables are a powerful tool in SQL for storing data temporarily. They are distinct from permanent tables in that they are not stored in the database's persistent data structures. This means they are not saved across sessions or database connections. This characteristic makes them ideal for holding intermediate results, data transformations, or data used for a specific query or procedure. Temporary tables are often used in conjunction with stored procedures or complex queries where you need to work with data that isn't meant to be part of the permanent database schema. They are also useful for testing or experimenting with data without affecting the main database tables. Temporary tables are a valuable tool for improving query performance and code organization.

Why Create Temp Table SQL is important

Temporary tables are crucial for managing intermediate data in complex queries and procedures. They help avoid cluttering permanent tables with temporary data and improve query performance by storing results for reuse. They also allow for more organized and modular code.

Create Temp Table SQL Example Usage


-- Create a temporary table named #temp_products
CREATE TABLE #temp_products (
    ProductID INT PRIMARY KEY,
    ProductName VARCHAR(50),
    Price DECIMAL(10, 2)
);

-- Insert some data into the temporary table
INSERT INTO #temp_products (ProductID, ProductName, Price)
VALUES
(1, 'Laptop', 1200.50),
(2, 'Mouse', 25.00),
(3, 'Keyboard', 75.00);

-- Select data from the temporary table
SELECT * FROM #temp_products;

-- Drop the temporary table (important to clean up)
DROP TABLE #temp_products;

Create Temp Table SQL Syntax

Common Mistakes

Forgetting to drop the temporary table after use, leading to wasted space and potential performance issues.
Using incorrect data types or constraints in the temporary table definition, leading to errors or unexpected behavior.
Not understanding the scope of temporary tables, leading to unintended data persistence or conflicts with other sessions.

Frequently Asked Questions (FAQs)

When is a temporary table preferable to a subquery or CTE?

Temporary tables shine when you need to reference the same intermediate result set multiple times inside a stored procedure or complex analytic workflow. Unlike a common table expression (CTE) or inline subquery, the data is materialized once, letting you join, filter, or aggregate it repeatedly without recomputation. This can lower total query cost and make debugging easier because you can SELECT * from the temp table at each step of development.

Do temporary tables persist after I close my database session?

No. By design, temporary tables live only for the lifespan of the current connection or stored procedure. When the session ends—or when the code explicitly drops them—the database automatically removes the table and its data from disk. That makes temp tables safe for quick experiments because they will never pollute your production schema.

How does Galaxy make working with temporary tables easier?

Galaxy’s modern SQL editor autocompletes temporary table names just like permanent tables, so you can iterate rapidly. The context-aware AI copilot can even suggest the CREATE TEMP TABLE statement from your existing query, optimize indexes, and flag when a temp table is unused. Because Galaxy retains run history in each workspace, your team can review or endorse queries that rely on temp tables without copying SQL into Slack or Notion.