The SQL Server DATALENGTH()
function is used to return the number of bytes used to represent any expression. This function is useful for determining the storage size of various data types, including text, binary, and image data.
SELECT DATALENGTH(expression);
The DATALENGTH()
function takes a single argument:
expression
: The expression whose byte length is to be calculated.Let's look at some examples of SQL Server DATALENGTH()
function queries:
SELECT DATALENGTH('Hello') AS length;
This query returns the number of bytes used to represent the string 'Hello'. The result will be:
length
------
5
SELECT first_name, DATALENGTH(first_name) AS length
FROM employees;
This query returns the byte length of the first_name
column for each employee.
SELECT DATALENGTH(CAST(12345 AS VARBINARY)) AS length;
This query returns the number of bytes used to represent the integer value 12345 when cast to a VARBINARY data type. The result will be:
length
------
2
Let's go through a complete example that includes creating a table, inserting data, and using the DATALENGTH()
function.
This step involves creating a new table named example_table
to store some sample data.
CREATE TABLE example_table (
id INT PRIMARY KEY,
description VARCHAR(50)
);
In this example, we create a table named example_table
with columns for id
and description
.
This step involves inserting some sample data into the example_table
.
INSERT INTO example_table (id, description) VALUES (1, 'Apple');
INSERT INTO example_table (id, description) VALUES (2, 'Banana');
INSERT INTO example_table (id, description) VALUES (3, 'Cherry');
Here, we insert data into the example_table
.
This step involves using the DATALENGTH()
function to calculate the byte length of the description
column.
SELECT id, description, DATALENGTH(description) AS length
FROM example_table;
This query retrieves the id
, description
, and the byte length of the description
column for each row in the example_table
. The result will be:
id description length
--- ------------ ------
1 Apple 5
2 Banana 6
3 Cherry 6
The SQL Server DATALENGTH()
function is a powerful tool for determining the storage size of various data types. Understanding how to use the DATALENGTH()
function and its syntax is essential for effective data processing and storage management in SQL Server.