Returns the left part of a character string with the specified number of characters.
Transact-SQL Syntax Conventions
LEFT ( character_expression , integer_expression )
Is an expression of character or binary data. character_expression can be a constant, variable, or column. character_expression can be of any data type, except text or ntext, that can be implicitly converted to varchar or nvarchar. Otherwise, use the CAST function to explicitly convert character_expression.
Is a positive integer that specifies how many characters of the character_expression will be returned. If integer_expression is negative, an error is returned. If integer_expression is type bigint and contains a large value, character_expression must be of a large data type such as varchar(max).
The integer_expression parameter counts a UTF-16 surrogate character as one character.
Returns varchar when character_expression is a non-Unicode character data type.
Returns nvarchar when character_expression is a Unicode character data type.
When using SC collations, the integer_expression parameter counts a UTF-16 surrogate pair as one character. For more information, see Collation and Unicode Support.
A. Using LEFT with a column
The following example returns the five leftmost characters of each product name.
USE AdventureWorks2012; GO SELECT LEFT(Name, 5) FROM Production.Product ORDER BY ProductID; GO
B. Using LEFT with a character string
The following example uses LEFT to return the two leftmost characters of the character string abcdefg.
SELECT LEFT('abcdefg',2) GO
Here is the result set.
-- ab (1 row(s) affected)
CAST and CONVERT (Transact-SQL)