SQL Server LEFT() Function: Returns Substring from Left

In SQL Server, the LEFT() function returns the specified number of characters from the left side of the specified string.

LEFT(character_expression, number_of_characters)

Parameters

1. character_expression: A string of type character or binary data. It can be a constant, variable, or column. It can be of any data type except text or ntext.
2. number_of_characters: A positive integer. The number of characters that will be extracted from the left side of the input string.

Return Value

Returns varchar data when the input string is a non-Unicode character data type and returns nvarchar when the input string is unicode.

Example 1:

The following example uses the LEFT() function to extract five characters from the left of an input string.

SELECT LEFT('Hello world', 5);

Example 2:

The following uses the LEFT() function with the column of the database table.

SELECT LEFT(FirstName, 3) AS Tag FROM Employee;

Example 3:

In the following example, the LEFT() function is used to extract the left three digits of the phone number as the Area Code.

SELECT FirstName, LEFT(phone, 3) AS AreaCode FROM Employee;