Introduction to PostgreSQL double precision Data Type

PostgreSQL is a powerful relational database management system that supports various data types, including double precision.

The double precision data type is a floating-point number with a precision of 15-17 digits, offering higher precision and a wider range compared to the float data type. It occupies 8 bytes of storage space.

Syntax

In PostgreSQL, the double precision type can be declared for a column using the following syntax:

column_name DOUBLE PRECISION

Use Cases

Due to its higher precision and wider range, the double precision data type is commonly used in situations that require higher precision calculations, such as scientific computing, engineering, and financial applications.

Examples

Here are some examples of using the double precision data type, including creating a table with a double precision column and inserting some data rows.

Create a table called employees with columns id, name, and salary, where salary is of data type double precision:

CREATE TABLE employees (
    id SERIAL PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    salary DOUBLE PRECISION NOT NULL
);

Insert some employee data rows:

INSERT INTO employees (name, salary) VALUES
    ('John Doe', 95000.50),
    ('Jane Smith', 128000.75),
    ('Bob Johnson', 75000.25);

Next, we can query the employees table and use the ROUND function to round the salary column:

-- Query the `employees` table and round the `salary` column
SELECT name, ROUND(salary) as rounded_salary
FROM employees;

The result will be:

 name         | rounded_salary
--------------+----------------
 John Doe     | 95001
 Jane Smith   | 128001
 Bob Johnson  | 75000

Conclusion

double precision provides higher precision and wider range, and is commonly used in situations that require higher precision calculations, such as scientific computing, engineering, and financial applications.