Create Temporary Table

-- Create a temporary table
CREATE TEMPORARY TABLE temp_table (
  id INT,
  name VARCHAR(255),
  age INT
);

-- Insert data into the temporary table
INSERT INTO temp_table (id, name, age)
VALUES
  (1, 'John Doe', 25),
  (2, 'Jane Doe', 30),
  (3, 'Bob Smith', 35);

-- Select data from the temporary table
SELECT * FROM temp_table;

-- Drop the temporary table
DROP TABLE temp_table;

Temporary Table Explanation

A temporary table in SQL is a table that is created temporarily and is automatically deleted when the session is closed. Temporary tables are useful for storing temporary data that needs to be used in a query or stored procedure.

Types of Temporary Tables

There are two types of temporary tables:

1. Local Temporary Table: A local temporary table is created using the CREATE TEMPORARY TABLE statement and is only accessible within the current session.
2. Global Temporary Table: A global temporary table is created using the CREATE GLOBAL TEMPORARY TABLE statement and is accessible across all sessions.

Temporary Table Use Cases

Temporary tables are useful in the following scenarios:

1. Complex Queries: Temporary tables can be used to store intermediate results in complex queries.
2. Data Transformation: Temporary tables can be used to transform data before inserting it into a permanent table.
3. Data Staging: Temporary tables can be used as a staging area for data before it is loaded into a data warehouse.

Best Practices

1. Use meaningful table names: Use descriptive and meaningful table names to avoid confusion.
2. Use indexes: Use indexes on temporary tables to improve query performance.
3. Avoid using temporary tables for large datasets: Temporary tables can consume a lot of memory and disk space, so avoid using them for large datasets.

Common Errors

1. Temporary table already exists: If a temporary table with the same name already exists, you will get an error.
2. Temporary table does not exist: If you try to access a temporary table that does not exist, you will get an error.

Example Use Case

Suppose we have a table called orders that contains information about customer orders. We want to find the total amount spent by each customer and store the result in a temporary table.

-- Create a temporary table
CREATE TEMPORARY TABLE temp_customer_orders (
  customer_id INT,
  total_amount DECIMAL(10, 2)
);

-- Insert data into the temporary table
INSERT INTO temp_customer_orders (customer_id, total_amount)
SELECT customer_id, SUM(order_amount)
FROM orders
GROUP BY customer_id;

-- Select data from the temporary table
SELECT * FROM temp_customer_orders;

In this example, we create a temporary table called temp_customer_orders and insert data into it using a SELECT statement. We then select data from the temporary table to get the total amount spent by each customer.