In SQL, a real data type is used to store single-precision floating-point numbers. It is commonly used to represent numbers with a decimal point that require less precision than the double data type. The real data type follows the IEEE 754 standard, which defines the representation and behavior of floating-point numbers in computer systems.
Real Data Type Syntax
The syntax for declaring a column with the real data type in SQL is as follows:
CREATE TABLE table_name ( column_name REAL );
Here, table_name represents the name of the table you want to create, and column_name represents the name of the column you want to define as a real data type.
Real Data Type Characteristics
The real data type has the following characteristics:
- Precision and Range:
- Decimal Places:
- Floating-Point Representation:
- Rounding Errors:
The real data type occupies 4 bytes of storage and can store values ranging from approximately -3.4E38 to 3.4E38.
A real number can have up to 7 decimal places of precision.
The real data type uses a binary representation for storing floating-point numbers, allowing for efficient computation and storage.
Due to its limited precision, rounding errors may occur when performing calculations with real numbers. It is important to be aware of these potential inaccuracies when working with this data type.
Let’s consider an example where we create a table to store product prices using the real data type:
CREATE TABLE products ( id INT, name VARCHAR(50), price REAL );
In this example, we have defined a table called “products” with three columns: “id” of integer data type, “name” of variable character data type, and “price” of real data type.
To insert data into the “products” table, you can use the INSERT INTO statement as follows:
INSERT INTO products (id, name, price) VALUES (1, 'Product 1', 9.99);
This statement inserts a row into the “products” table with an ID of 1, a name of “Product 1”, and a price of 9.99.
To retrieve data from the “products” table, you can use the SELECT statement as follows:
SELECT * FROM products;
This statement selects all columns from the “products” table and returns the result set containing all rows and their respective values.
The real data type in SQL provides a way to store single-precision floating-point numbers with limited precision. It is useful when you need to represent decimal numbers that do not require high precision. By understanding its characteristics and usage examples, you can effectively work with real data types in your SQL queries.