Guide: Creating Temporary Tables in PostgreSQL
Tags: apacheage, database, postgres, postgressql
Published: 2023-08-28 16:29:02

In this guide, we will take a look at the process of creating temporary tables in PostgreSQL.

### Understanding Temporary Tables
Temporary tables in PostgreSQL are a special type of table that exist only for the duration of a database session. They are very useful when you need to store and process data temporarily without the need for permanent storage. Temporary tables are created within a specific schema and are automatically dropped at the end of the session or transaction.

### Creating Temporary Tables
Let's dive into the steps of creating temporary tables in PostgreSQL:

**Step 1: Connect to the Database**
Before creating any table, you need to establish a connection to your PostgreSQL database using a client of your choice. This can be achieved using tools like psql, a popular command-line interface, or through graphical user interfaces like pgAdmin.

**Step 2: Syntax for Creating Temporary Tables**
The syntax for creating a temporary table is similar to that of a regular table, with one key difference: the use of the `TEMPORARY` keyword. Here's a basic template:

```
CREATE TEMPORARY TABLE table_name (
    column1 data_type,
    column2 data_type,
    -- Define other columns here
);
```

For example:
```
my_db=# CREATE TEMPORARY TABLE temp_table (
    id SERIAL PRIMARY KEY NOT NULL
    name VARCHAR(25) NOT NULL);
CREATE TABLE
```

**Step 3: Populating the Temporary Table**
Once you've defined the structure of your temporary table, you can populate it with data using the standard INSERT INTO statement. This allows you to work with the temporary data just like you would with any other table.

```
my_db=# INSERT INTO temp_table(name) VALUES('Daniel'),
my_db-# ('Mary'), ('George');
INSERT 0 3
```

```
my_db=# SELECT * FROM temp_table;
 id |  name
----+--------
  1 | Daniel
  2 | Mary
  3 | George
(3 rows)
```

**Step 4: Performing Operations**
Temporary tables can be used for a variety of purposes, such as:

**1. Intermediate Calculations:** When you need to perform complex calculations or data transformations, temporary tables provide a way to store intermediate results before arriving at the final output.

**2. Session-Specific Data:** Temporary tables are session-specific, which means different users can work with their own copies of the same temporary table without conflicting with each other's data.

**3. Batch Processing:** Temporary tables are commonly used in batch processing scenarios, where you can load data into a temporary table, manipulate it, and then insert the processed data into your main tables.

**Step 5: Dropping Temporary Tables**
Remember that temporary tables are automatically dropped at the end of your session or transaction. But, if you want to explicitly drop a temporary table before that, you can use the `DROP TABLE` statement:

```
DROP TABLE IF EXISTS table_name;
```

For example:
```
my_db=# DROP TABLE IF EXISTS temp_table;
DROP TABLE
```

### Conclusion
Creating temporary tables in PostgreSQL offers a versatile and efficient way to manage and process data within the context of a session. These tables are particularly handy for intermediate data storage during complex calculations, batch processing, and more. By understanding the syntax and use cases of temporary tables, you can unlock a powerful tool in your PostgreSQL toolkit. Whether you're an analyst, developer, or database administrator, temporary tables can enhance your data manipulation capabilities and streamline your workflows.

### References
- [PostgreSQL CREATE TABLES](https://www.postgresql.org/docs/current/sql-createtable.html)
- [PostgreSQL Installation Procedure](https://www.postgresql.org/docs/current/install-procedure.html#CONFIGURE-OPTIONS)
- Visit Apache AGE Website: https://age.apache.org/
- Visit Apache AGE GitHub: https://github.com/apache/age
- Visit Apache AGE Viewer GitHub: https://github.com/apache/age-viewer